diff --git a/keyserver/src/push/crypto.js b/keyserver/src/push/crypto.js
index 11aec6f18..8591deda5 100644
--- a/keyserver/src/push/crypto.js
+++ b/keyserver/src/push/crypto.js
@@ -1,480 +1,484 @@
 // @flow
 
 import type { EncryptResult } from '@commapp/olm';
 import apn from '@parse/node-apn';
 import crypto from 'crypto';
 import invariant from 'invariant';
 import _cloneDeep from 'lodash/fp/cloneDeep.js';
 
 import type {
   PlainTextWebNotification,
   PlainTextWebNotificationPayload,
   WebNotification,
   PlainTextWNSNotification,
   WNSNotification,
 } from 'lib/types/notif-types.js';
 import { toBase64URL } from 'lib/utils/base64.js';
 
 import type {
   AndroidNotification,
   AndroidNotificationPayload,
   AndroidNotificationRescind,
   NotificationTargetDevice,
 } from './types.js';
 import { encryptAndUpdateOlmSession } from '../updaters/olm-session-updater.js';
 import { encrypt, generateKey } from '../utils/aes-crypto-utils.js';
 import { getOlmUtility } from '../utils/olm-utils.js';
 
 async function encryptAPNsNotification(
   cookieID: string,
   notification: apn.Notification,
   codeVersion?: ?number,
   notificationSizeValidator?: apn.Notification => boolean,
 ): Promise<{
   +notification: apn.Notification,
   +payloadSizeExceeded: boolean,
   +encryptedPayloadHash?: string,
   +encryptionOrder?: number,
 }> {
   invariant(
     !notification.collapseId,
     `Collapse ID can't be directly stored in apn.Notification object due ` +
       `to security reasons. Please put it in payload property`,
   );
 
   const encryptedNotification = new apn.Notification();
 
   encryptedNotification.id = notification.id;
   encryptedNotification.payload.id = notification.id;
+  encryptedNotification.payload.keyserverID = notification.payload.keyserverID;
   encryptedNotification.topic = notification.topic;
   encryptedNotification.sound = notification.aps.sound;
   encryptedNotification.pushType = 'alert';
   encryptedNotification.mutableContent = true;
 
-  const { id, ...payloadSansId } = notification.payload;
+  const { id, keyserverID, ...payloadSansUnencryptedData } =
+    notification.payload;
   const unencryptedPayload = {
-    ...payloadSansId,
+    ...payloadSansUnencryptedData,
     badge: notification.aps.badge.toString(),
     merged: notification.body,
   };
 
   try {
     const unencryptedSerializedPayload = JSON.stringify(unencryptedPayload);
 
     let dbPersistCondition;
     if (notificationSizeValidator) {
       dbPersistCondition = ({
         serializedPayload,
       }: {
         +[string]: EncryptResult,
       }) => {
         const notifCopy = _cloneDeep(encryptedNotification);
         notifCopy.payload.encryptedPayload = serializedPayload.body;
         return notificationSizeValidator(notifCopy);
       };
     }
     const {
       encryptedMessages: { serializedPayload },
       dbPersistConditionViolated,
       encryptionOrder,
     } = await encryptAndUpdateOlmSession(
       cookieID,
       'notifications',
       {
         serializedPayload: unencryptedSerializedPayload,
       },
       dbPersistCondition,
     );
 
     encryptedNotification.payload.encryptedPayload = serializedPayload.body;
 
     if (codeVersion && codeVersion >= 254 && codeVersion % 2 === 0) {
       encryptedNotification.aps = {
         alert: { body: 'ENCRYPTED' },
         ...encryptedNotification.aps,
       };
     }
 
     const encryptedPayloadHash = getOlmUtility().sha256(serializedPayload.body);
     return {
       notification: encryptedNotification,
       payloadSizeExceeded: !!dbPersistConditionViolated,
       encryptedPayloadHash,
       encryptionOrder,
     };
   } catch (e) {
     console.log('Notification encryption failed: ' + e);
 
     encryptedNotification.body = notification.body;
     encryptedNotification.threadId = notification.payload.threadID;
     invariant(
       typeof notification.aps.badge === 'number',
       'Unencrypted notification must have badge as a number',
     );
     encryptedNotification.badge = notification.aps.badge;
 
     encryptedNotification.payload = {
       ...encryptedNotification.payload,
       ...notification.payload,
       encryptionFailed: 1,
     };
     return {
       notification: encryptedNotification,
       payloadSizeExceeded: notificationSizeValidator
         ? notificationSizeValidator(_cloneDeep(encryptedNotification))
         : false,
     };
   }
 }
 
 async function encryptAndroidNotificationPayload<T>(
   cookieID: string,
   unencryptedPayload: T,
   payloadSizeValidator?: (T | { +encryptedPayload: string }) => boolean,
 ): Promise<{
   +resultPayload: T | { +encryptedPayload: string },
   +payloadSizeExceeded: boolean,
   +encryptionOrder?: number,
 }> {
   try {
     const unencryptedSerializedPayload = JSON.stringify(unencryptedPayload);
     if (!unencryptedSerializedPayload) {
       return {
         resultPayload: unencryptedPayload,
         payloadSizeExceeded: payloadSizeValidator
           ? payloadSizeValidator(unencryptedPayload)
           : false,
       };
     }
 
     let dbPersistCondition;
     if (payloadSizeValidator) {
       dbPersistCondition = ({
         serializedPayload,
       }: {
         +[string]: EncryptResult,
       }) => payloadSizeValidator({ encryptedPayload: serializedPayload.body });
     }
 
     const {
       encryptedMessages: { serializedPayload },
       dbPersistConditionViolated,
       encryptionOrder,
     } = await encryptAndUpdateOlmSession(
       cookieID,
       'notifications',
       {
         serializedPayload: unencryptedSerializedPayload,
       },
       dbPersistCondition,
     );
     return {
       resultPayload: { encryptedPayload: serializedPayload.body },
       payloadSizeExceeded: !!dbPersistConditionViolated,
       encryptionOrder,
     };
   } catch (e) {
     console.log('Notification encryption failed: ' + e);
     const resultPayload = {
       encryptionFailed: '1',
       ...unencryptedPayload,
     };
     return {
       resultPayload,
       payloadSizeExceeded: payloadSizeValidator
         ? payloadSizeValidator(resultPayload)
         : false,
     };
   }
 }
 
 async function encryptAndroidNotification(
   cookieID: string,
   notification: AndroidNotification,
   notificationSizeValidator?: AndroidNotification => boolean,
 ): Promise<{
   +notification: AndroidNotification,
   +payloadSizeExceeded: boolean,
   +encryptionOrder?: number,
 }> {
-  const { id, badgeOnly, ...unencryptedPayload } = notification.data;
-  let unencryptedData = { badgeOnly };
+  const { id, keyserverID, badgeOnly, ...unencryptedPayload } =
+    notification.data;
+  let unencryptedData = { badgeOnly, keyserverID };
   if (id) {
     unencryptedData = { ...unencryptedData, id };
   }
 
   let payloadSizeValidator;
   if (notificationSizeValidator) {
     payloadSizeValidator = (
       payload: AndroidNotificationPayload | { +encryptedPayload: string },
     ) => {
       return notificationSizeValidator({
         data: { ...unencryptedData, ...payload },
       });
     };
   }
   const { resultPayload, payloadSizeExceeded, encryptionOrder } =
     await encryptAndroidNotificationPayload(
       cookieID,
       unencryptedPayload,
       payloadSizeValidator,
     );
   return {
     notification: {
       data: {
         ...unencryptedData,
         ...resultPayload,
       },
     },
     payloadSizeExceeded,
     encryptionOrder,
   };
 }
 
 async function encryptAndroidNotificationRescind(
   cookieID: string,
   notification: AndroidNotificationRescind,
 ): Promise<AndroidNotificationRescind> {
   // We don't validate payload size for rescind
   // since they are expected to be small and
   // never exceed any FCM limit
+  const { keyserverID, ...unencryptedPayload } = notification.data;
   const { resultPayload } = await encryptAndroidNotificationPayload(
     cookieID,
-    notification.data,
+    unencryptedPayload,
   );
   return {
-    data: resultPayload,
+    data: { keyserverID, ...resultPayload },
   };
 }
 
 async function encryptBasicPayload<T>(
   cookieID: string,
   basicPayload: T,
 ): Promise<
   | { +encryptedPayload: string, +encryptionOrder?: number }
   | { ...T, +encryptionFailed: '1' },
 > {
   const unencryptedSerializedPayload = JSON.stringify(basicPayload);
 
   if (!unencryptedSerializedPayload) {
     return { ...basicPayload, encryptionFailed: '1' };
   }
 
   try {
     const {
       encryptedMessages: { serializedPayload },
       encryptionOrder,
     } = await encryptAndUpdateOlmSession(cookieID, 'notifications', {
       serializedPayload: unencryptedSerializedPayload,
     });
 
     return {
       encryptedPayload: serializedPayload.body,
       encryptionOrder,
     };
   } catch (e) {
     console.log('Notification encryption failed: ' + e);
     return {
       ...basicPayload,
       encryptionFailed: '1',
     };
   }
 }
 
 async function encryptWebNotification(
   cookieID: string,
   notification: PlainTextWebNotification,
 ): Promise<{ +notification: WebNotification, +encryptionOrder?: number }> {
   const { id, ...payloadSansId } = notification;
   const { encryptionOrder, ...encryptionResult } =
     await encryptBasicPayload<PlainTextWebNotificationPayload>(
       cookieID,
       payloadSansId,
     );
   return { notification: { id, ...encryptionResult }, encryptionOrder };
 }
 
 async function encryptWNSNotification(
   cookieID: string,
   notification: PlainTextWNSNotification,
 ): Promise<{ +notification: WNSNotification, +encryptionOrder?: number }> {
   const { encryptionOrder, ...encryptionResult } =
     await encryptBasicPayload<PlainTextWNSNotification>(cookieID, notification);
   return { notification: encryptionResult, encryptionOrder };
 }
 
 function prepareEncryptedAPNsNotifications(
   devices: $ReadOnlyArray<NotificationTargetDevice>,
   notification: apn.Notification,
   codeVersion?: ?number,
   notificationSizeValidator?: apn.Notification => boolean,
 ): Promise<
   $ReadOnlyArray<{
     +cookieID: string,
     +deviceToken: string,
     +notification: apn.Notification,
     +payloadSizeExceeded: boolean,
     +encryptedPayloadHash?: string,
     +encryptionOrder?: number,
   }>,
 > {
   const notificationPromises = devices.map(
     async ({ cookieID, deviceToken }) => {
       const notif = await encryptAPNsNotification(
         cookieID,
         notification,
         codeVersion,
         notificationSizeValidator,
       );
       return { cookieID, deviceToken, ...notif };
     },
   );
   return Promise.all(notificationPromises);
 }
 
 function prepareEncryptedIOSNotificationRescind(
   devices: $ReadOnlyArray<NotificationTargetDevice>,
   notification: apn.Notification,
   codeVersion?: ?number,
 ): Promise<
   $ReadOnlyArray<{
     +cookieID: string,
     +deviceToken: string,
     +notification: apn.Notification,
   }>,
 > {
   const notificationPromises = devices.map(
     async ({ deviceToken, cookieID }) => {
       const { notification: notif } = await encryptAPNsNotification(
         cookieID,
         notification,
         codeVersion,
       );
       return { deviceToken, cookieID, notification: notif };
     },
   );
   return Promise.all(notificationPromises);
 }
 
 function prepareEncryptedAndroidNotifications(
   devices: $ReadOnlyArray<NotificationTargetDevice>,
   notification: AndroidNotification,
   notificationSizeValidator?: (notification: AndroidNotification) => boolean,
 ): Promise<
   $ReadOnlyArray<{
     +cookieID: string,
     +deviceToken: string,
     +notification: AndroidNotification,
     +payloadSizeExceeded: boolean,
     +encryptionOrder?: number,
   }>,
 > {
   const notificationPromises = devices.map(
     async ({ deviceToken, cookieID }) => {
       const notif = await encryptAndroidNotification(
         cookieID,
         notification,
         notificationSizeValidator,
       );
       return { deviceToken, cookieID, ...notif };
     },
   );
   return Promise.all(notificationPromises);
 }
 
 function prepareEncryptedAndroidNotificationRescinds(
   devices: $ReadOnlyArray<NotificationTargetDevice>,
   notification: AndroidNotificationRescind,
 ): Promise<
   $ReadOnlyArray<{
     +cookieID: string,
     +deviceToken: string,
     +notification: AndroidNotificationRescind,
     +encryptionOrder?: number,
   }>,
 > {
   const notificationPromises = devices.map(
     async ({ deviceToken, cookieID }) => {
       const notif = await encryptAndroidNotificationRescind(
         cookieID,
         notification,
       );
       return { deviceToken, cookieID, notification: notif };
     },
   );
   return Promise.all(notificationPromises);
 }
 
 function prepareEncryptedWebNotifications(
   devices: $ReadOnlyArray<NotificationTargetDevice>,
   notification: PlainTextWebNotification,
 ): Promise<
   $ReadOnlyArray<{
     +deviceToken: string,
     +notification: WebNotification,
     +encryptionOrder?: number,
   }>,
 > {
   const notificationPromises = devices.map(
     async ({ deviceToken, cookieID }) => {
       const notif = await encryptWebNotification(cookieID, notification);
       return { ...notif, deviceToken };
     },
   );
   return Promise.all(notificationPromises);
 }
 
 function prepareEncryptedWNSNotifications(
   devices: $ReadOnlyArray<NotificationTargetDevice>,
   notification: PlainTextWNSNotification,
 ): Promise<
   $ReadOnlyArray<{
     +deviceToken: string,
     +notification: WNSNotification,
     +encryptionOrder?: number,
   }>,
 > {
   const notificationPromises = devices.map(
     async ({ deviceToken, cookieID }) => {
       const notif = await encryptWNSNotification(cookieID, notification);
       return { ...notif, deviceToken };
     },
   );
   return Promise.all(notificationPromises);
 }
 
 async function encryptBlobPayload(payload: string): Promise<{
   +encryptionKey: string,
   +encryptedPayload: Blob,
   +encryptedPayloadHash: string,
 }> {
   const encryptionKey = await generateKey();
   const encryptedPayload = await encrypt(
     encryptionKey,
     new TextEncoder().encode(payload),
   );
   const encryptedPayloadBuffer = Buffer.from(encryptedPayload);
   const blobHashBase64 = await crypto
     .createHash('sha256')
     .update(encryptedPayloadBuffer)
     .digest('base64');
   const blobHash = toBase64URL(blobHashBase64);
 
   const payloadBlob = new Blob([encryptedPayloadBuffer]);
   const encryptionKeyString = Buffer.from(encryptionKey).toString('base64');
   return {
     encryptionKey: encryptionKeyString,
     encryptedPayload: payloadBlob,
     encryptedPayloadHash: blobHash,
   };
 }
 
 export {
   prepareEncryptedAPNsNotifications,
   prepareEncryptedIOSNotificationRescind,
   prepareEncryptedAndroidNotifications,
   prepareEncryptedAndroidNotificationRescinds,
   prepareEncryptedWebNotifications,
   prepareEncryptedWNSNotifications,
   encryptBlobPayload,
 };
diff --git a/keyserver/src/push/rescind.js b/keyserver/src/push/rescind.js
index b33853c81..1f013d463 100644
--- a/keyserver/src/push/rescind.js
+++ b/keyserver/src/push/rescind.js
@@ -1,379 +1,389 @@
 // @flow
 
 import apn from '@parse/node-apn';
 import type { ResponseFailure } from '@parse/node-apn';
 import type { FirebaseError } from 'firebase-admin';
 import invariant from 'invariant';
 
 import type { PlatformDetails } from 'lib/types/device-types.js';
 import { threadSubscriptions } from 'lib/types/subscription-types.js';
 import { threadPermissions } from 'lib/types/thread-permission-types.js';
 import { promiseAll } from 'lib/utils/promises.js';
 import { tID } from 'lib/utils/validation-utils.js';
 
 import {
   prepareEncryptedAndroidNotificationRescinds,
   prepareEncryptedIOSNotificationRescind,
 } from './crypto.js';
 import { getAPNsNotificationTopic } from './providers.js';
 import type {
   NotificationTargetDevice,
   TargetedAndroidNotification,
   TargetedAPNsNotification,
 } from './types.js';
 import {
   apnPush,
   fcmPush,
   type APNPushResult,
   type FCMPushResult,
 } from './utils.js';
 import createIDs from '../creators/id-creator.js';
 import { dbQuery, SQL } from '../database/database.js';
 import type { SQLStatementType } from '../database/types.js';
+import { thisKeyserverID } from '../user/identity.js';
 import { validateOutput } from '../utils/validation-utils.js';
 
 type ParsedDelivery = {
   +platform: 'ios' | 'macos' | 'android',
   +codeVersion: ?number,
   +stateVersion: ?number,
   +notificationID: string,
   +deviceTokens: $ReadOnlyArray<string>,
 };
 
 type RescindDelivery = {
   source: 'rescind',
   rescindedID: string,
   errors?:
     | $ReadOnlyArray<FirebaseError | mixed>
     | $ReadOnlyArray<ResponseFailure>,
 };
 
 async function rescindPushNotifs(
   notifCondition: SQLStatementType,
   inputCountCondition?: SQLStatementType,
 ) {
   const notificationExtractString = `$.${threadSubscriptions.home}`;
   const visPermissionExtractString = `$.${threadPermissions.VISIBLE}.value`;
   const fetchQuery = SQL`
     SELECT n.id, n.user, n.thread, n.message, n.delivery, n.collapse_key, COUNT(
   `;
   fetchQuery.append(inputCountCondition ? inputCountCondition : SQL`m.thread`);
   fetchQuery.append(SQL`
       ) AS unread_count
     FROM notifications n
-    LEFT JOIN memberships m ON m.user = n.user 
+    LEFT JOIN memberships m ON m.user = n.user
       AND m.last_message > m.last_read_message 
       AND m.role > 0 
       AND JSON_EXTRACT(subscription, ${notificationExtractString})
       AND JSON_EXTRACT(permissions, ${visPermissionExtractString})
     WHERE n.rescinded = 0 AND
   `);
   fetchQuery.append(notifCondition);
   fetchQuery.append(SQL` GROUP BY n.id, m.user`);
-  const [fetchResult] = await dbQuery(fetchQuery);
+  const [[fetchResult], keyserverID] = await Promise.all([
+    dbQuery(fetchQuery),
+    thisKeyserverID(),
+  ]);
 
   const allDeviceTokens = new Set<string>();
   const parsedDeliveries: { [string]: $ReadOnlyArray<ParsedDelivery> } = {};
 
   for (const row of fetchResult) {
     const rawDelivery = JSON.parse(row.delivery);
     const deliveries = Array.isArray(rawDelivery) ? rawDelivery : [rawDelivery];
     const id = row.id.toString();
 
     const rowParsedDeliveries = [];
 
     for (const delivery of deliveries) {
       if (
         delivery.iosID ||
         delivery.deviceType === 'ios' ||
         delivery.deviceType === 'macos'
       ) {
         const deviceTokens = delivery.iosDeviceTokens ?? delivery.deviceTokens;
         rowParsedDeliveries.push({
           notificationID: delivery.iosID,
           codeVersion: delivery.codeVersion,
           stateVersion: delivery.stateVersion,
           platform: delivery.deviceType ?? 'ios',
           deviceTokens,
         });
         deviceTokens.forEach(deviceToken => allDeviceTokens.add(deviceToken));
       } else if (delivery.androidID || delivery.deviceType === 'android') {
         const deviceTokens =
           delivery.androidDeviceTokens ?? delivery.deviceTokens;
         rowParsedDeliveries.push({
           notificationID: row.collapse_key ? row.collapse_key : id,
           codeVersion: delivery.codeVersion,
           stateVersion: delivery.stateVersion,
           platform: 'android',
           deviceTokens,
         });
         deviceTokens.forEach(deviceToken => allDeviceTokens.add(deviceToken));
       }
     }
     parsedDeliveries[id] = rowParsedDeliveries;
   }
   const deviceTokenToCookieID = await getDeviceTokenToCookieID(allDeviceTokens);
 
   const deliveryPromises: {
     [string]: Promise<APNPushResult> | Promise<FCMPushResult>,
   } = {};
   const notifInfo = {};
   const rescindedIDs = [];
 
   for (const row of fetchResult) {
     const id = row.id.toString();
     const threadID = row.thread.toString();
 
     notifInfo[id] = {
       userID: row.user.toString(),
       threadID,
       messageID: row.message.toString(),
     };
 
     for (const delivery of parsedDeliveries[id]) {
       let platformDetails: PlatformDetails = { platform: delivery.platform };
       if (delivery.codeVersion) {
         platformDetails = {
           ...platformDetails,
           codeVersion: delivery.codeVersion,
         };
       }
       if (delivery.stateVersion) {
         platformDetails = {
           ...platformDetails,
           stateVersion: delivery.stateVersion,
         };
       }
 
       if (delivery.platform === 'ios') {
         const devices = delivery.deviceTokens.map(deviceToken => ({
           deviceToken,
           cookieID: deviceTokenToCookieID[deviceToken],
         }));
         const deliveryPromise = (async () => {
           const targetedNotifications = await prepareIOSNotification(
+            keyserverID,
             delivery.notificationID,
             row.unread_count,
             threadID,
             platformDetails,
             devices,
           );
           return await apnPush({
             targetedNotifications,
             platformDetails: {
               platform: 'ios',
               codeVersion: delivery.codeVersion,
             },
           });
         })();
         deliveryPromises[id] = deliveryPromise;
       } else if (delivery.platform === 'android') {
         const devices = delivery.deviceTokens.map(deviceToken => ({
           deviceToken,
           cookieID: deviceTokenToCookieID[deviceToken],
         }));
         const deliveryPromise = (async () => {
           const targetedNotifications = await prepareAndroidNotification(
+            keyserverID,
             delivery.notificationID,
             row.unread_count,
             threadID,
             platformDetails,
             devices,
           );
           return await fcmPush({
             targetedNotifications,
             codeVersion: delivery.codeVersion,
           });
         })();
         deliveryPromises[id] = deliveryPromise;
       }
     }
     rescindedIDs.push(id);
   }
 
   const numRescinds = Object.keys(deliveryPromises).length;
   const dbIDsPromise: Promise<?Array<string>> = (async () => {
     if (numRescinds === 0) {
       return undefined;
     }
     return await createIDs('notifications', numRescinds);
   })();
   const rescindPromise: Promise<mixed> = (async () => {
     if (rescindedIDs.length === 0) {
       return undefined;
     }
     const rescindQuery = SQL`
       UPDATE notifications SET rescinded = 1 WHERE id IN (${rescindedIDs})
     `;
     return await dbQuery(rescindQuery);
   })();
 
   const [deliveryResults, dbIDs] = await Promise.all([
     promiseAll(deliveryPromises),
     dbIDsPromise,
     rescindPromise,
   ]);
 
   const newNotifRows = [];
   if (numRescinds > 0) {
     invariant(dbIDs, 'dbIDs should be set');
     for (const rescindedID in deliveryResults) {
       const delivery: RescindDelivery = {
         source: 'rescind',
         rescindedID,
       };
       const { errors } = deliveryResults[rescindedID];
       if (errors) {
         delivery.errors = errors;
       }
       const dbID = dbIDs.shift();
       const { userID, threadID, messageID } = notifInfo[rescindedID];
       newNotifRows.push([
         dbID,
         userID,
         threadID,
         messageID,
         null,
         JSON.stringify([delivery]),
         1,
       ]);
     }
   }
   if (newNotifRows.length > 0) {
     const insertQuery = SQL`
       INSERT INTO notifications
         (id, user, thread, message, collapse_key, delivery, rescinded)
       VALUES ${newNotifRows}
     `;
     await dbQuery(insertQuery);
   }
 }
 
 async function getDeviceTokenToCookieID(
   deviceTokens: Set<string>,
 ): Promise<{ +[string]: string }> {
   if (deviceTokens.size === 0) {
     return {};
   }
   const deviceTokenToCookieID = {};
   const fetchCookiesQuery = SQL`
     SELECT id, device_token FROM cookies 
     WHERE device_token IN (${[...deviceTokens]})
   `;
   const [fetchResult] = await dbQuery(fetchCookiesQuery);
   for (const row of fetchResult) {
     deviceTokenToCookieID[row.device_token.toString()] = row.id.toString();
   }
   return deviceTokenToCookieID;
 }
 
 async function conditionallyEncryptNotification<T>(
   notification: T,
   codeVersion: ?number,
   devices: $ReadOnlyArray<NotificationTargetDevice>,
   encryptCallback: (
     devices: $ReadOnlyArray<NotificationTargetDevice>,
     notification: T,
     codeVersion?: ?number,
   ) => Promise<
     $ReadOnlyArray<{
       +notification: T,
       +cookieID: string,
       +deviceToken: string,
       +encryptionOrder?: number,
     }>,
   >,
 ): Promise<$ReadOnlyArray<{ +deviceToken: string, +notification: T }>> {
   const shouldBeEncrypted = codeVersion && codeVersion >= 233;
   if (!shouldBeEncrypted) {
     return devices.map(({ deviceToken }) => ({
       notification,
       deviceToken,
     }));
   }
   const notifications = await encryptCallback(
     devices,
     notification,
     codeVersion,
   );
   return notifications.map(({ deviceToken, notification: notif }) => ({
     deviceToken,
     notification: notif,
   }));
 }
 
 async function prepareIOSNotification(
+  keyserverID: string,
   iosID: string,
   unreadCount: number,
   threadID: string,
   platformDetails: PlatformDetails,
   devices: $ReadOnlyArray<NotificationTargetDevice>,
 ): Promise<$ReadOnlyArray<TargetedAPNsNotification>> {
   threadID = await validateOutput(platformDetails, tID, threadID);
   const { codeVersion } = platformDetails;
 
   const notification = new apn.Notification();
   notification.topic = getAPNsNotificationTopic({
     platform: 'ios',
     codeVersion,
   });
 
   if (codeVersion && codeVersion > 198) {
     notification.mutableContent = true;
     notification.pushType = 'alert';
     notification.badge = unreadCount;
   } else {
     notification.priority = 5;
     notification.contentAvailable = true;
     notification.pushType = 'background';
   }
   notification.payload =
     codeVersion && codeVersion > 135
       ? {
           backgroundNotifType: 'CLEAR',
           notificationId: iosID,
           setUnreadStatus: true,
           threadID,
+          keyserverID,
         }
       : {
           managedAps: {
             action: 'CLEAR',
             notificationId: iosID,
           },
         };
   return await conditionallyEncryptNotification(
     notification,
     codeVersion,
     devices,
     prepareEncryptedIOSNotificationRescind,
   );
 }
 
 async function prepareAndroidNotification(
+  keyserverID: string,
   notifID: string,
   unreadCount: number,
   threadID: string,
   platformDetails: PlatformDetails,
   devices: $ReadOnlyArray<NotificationTargetDevice>,
 ): Promise<$ReadOnlyArray<TargetedAndroidNotification>> {
   threadID = await validateOutput(platformDetails, tID, threadID);
   const { codeVersion } = platformDetails;
 
   const notification = {
     data: {
       badge: unreadCount.toString(),
       rescind: 'true',
       rescindID: notifID,
       setUnreadStatus: 'true',
       threadID,
+      keyserverID,
     },
   };
   return await conditionallyEncryptNotification(
     notification,
     codeVersion,
     devices,
     prepareEncryptedAndroidNotificationRescinds,
   );
 }
 
 export { rescindPushNotifs };
diff --git a/keyserver/src/push/send.js b/keyserver/src/push/send.js
index 5c3b5aca8..edd621104 100644
--- a/keyserver/src/push/send.js
+++ b/keyserver/src/push/send.js
@@ -1,1810 +1,1833 @@
 // @flow
 
 import type { ResponseFailure } from '@parse/node-apn';
 import apn from '@parse/node-apn';
 import invariant from 'invariant';
 import _cloneDeep from 'lodash/fp/cloneDeep.js';
 import _flow from 'lodash/fp/flow.js';
 import _groupBy from 'lodash/fp/groupBy.js';
 import _mapValues from 'lodash/fp/mapValues.js';
 import _pickBy from 'lodash/fp/pickBy.js';
 import type { QueryResults } from 'mysql';
 import t from 'tcomb';
 import uuidv4 from 'uuid/v4.js';
 
 import { oldValidUsernameRegex } from 'lib/shared/account-utils.js';
 import { isUserMentioned } from 'lib/shared/mention-utils.js';
 import {
   createMessageInfo,
   shimUnsupportedRawMessageInfos,
   sortMessageInfoList,
 } from 'lib/shared/message-utils.js';
 import { messageSpecs } from 'lib/shared/messages/message-specs.js';
 import { notifTextsForMessageInfo } from 'lib/shared/notif-utils.js';
 import {
   rawThreadInfoFromServerThreadInfo,
   threadInfoFromRawThreadInfo,
 } from 'lib/shared/thread-utils.js';
 import { hasMinCodeVersion } from 'lib/shared/version-utils.js';
 import type { Platform, PlatformDetails } from 'lib/types/device-types.js';
 import { messageTypes } from 'lib/types/message-types-enum.js';
 import {
   type MessageData,
   type RawMessageInfo,
   rawMessageInfoValidator,
 } from 'lib/types/message-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import type { ResolvedNotifTexts } from 'lib/types/notif-types.js';
 import { resolvedNotifTextsValidator } from 'lib/types/notif-types.js';
 import type { ServerThreadInfo } from 'lib/types/thread-types.js';
 import { updateTypes } from 'lib/types/update-types-enum.js';
 import { type GlobalUserInfo } from 'lib/types/user-types.js';
 import { values } from 'lib/utils/objects.js';
 import { tID, tPlatformDetails, tShape } from 'lib/utils/validation-utils.js';
 
 import {
   prepareEncryptedAndroidNotifications,
   prepareEncryptedAPNsNotifications,
   prepareEncryptedWebNotifications,
   prepareEncryptedWNSNotifications,
 } from './crypto.js';
 import { getAPNsNotificationTopic } from './providers.js';
 import { rescindPushNotifs } from './rescind.js';
 import type {
   AndroidNotification,
   NotificationTargetDevice,
   TargetedAndroidNotification,
   TargetedAPNsNotification,
   TargetedWebNotification,
   TargetedWNSNotification,
 } from './types.js';
 import {
   apnMaxNotificationPayloadByteSize,
   apnPush,
   fcmMaxNotificationPayloadByteSize,
   fcmPush,
   getUnreadCounts,
   webPush,
   type WebPushError,
   wnsMaxNotificationPayloadByteSize,
   wnsPush,
   type WNSPushError,
 } from './utils.js';
 import createIDs from '../creators/id-creator.js';
 import { createUpdates } from '../creators/update-creator.js';
 import { dbQuery, mergeOrConditions, SQL } from '../database/database.js';
 import type { CollapsableNotifInfo } from '../fetchers/message-fetchers.js';
 import { fetchCollapsableNotifs } from '../fetchers/message-fetchers.js';
 import { fetchServerThreadInfos } from '../fetchers/thread-fetchers.js';
 import { fetchUserInfos } from '../fetchers/user-fetchers.js';
 import type { Viewer } from '../session/viewer.js';
+import { thisKeyserverID } from '../user/identity.js';
 import { getENSNames } from '../utils/ens-cache.js';
 import { validateOutput } from '../utils/validation-utils.js';
 
 export type Device = {
   +platform: Platform,
   +deviceToken: string,
   +cookieID: string,
   +codeVersion: ?number,
   +stateVersion: ?number,
   +majorDesktopVersion: ?number,
 };
 
 export type PushUserInfo = {
   +devices: Device[],
   // messageInfos and messageDatas have the same key
   +messageInfos: RawMessageInfo[],
   +messageDatas: MessageData[],
 };
 type Delivery = PushDelivery | { collapsedInto: string };
 type NotificationRow = {
   +dbID: string,
   +userID: string,
   +threadID?: ?string,
   +messageID?: ?string,
   +collapseKey?: ?string,
   +deliveries: Delivery[],
 };
 export type PushInfo = { [userID: string]: PushUserInfo };
 
 async function sendPushNotifs(pushInfo: PushInfo) {
   if (Object.keys(pushInfo).length === 0) {
     return;
   }
 
+  const keyserverID = await thisKeyserverID();
+
   const [
     unreadCounts,
     { usersToCollapsableNotifInfo, serverThreadInfos, userInfos },
     dbIDs,
   ] = await Promise.all([
     getUnreadCounts(Object.keys(pushInfo)),
     fetchInfos(pushInfo),
     createDBIDs(pushInfo),
   ]);
 
   const preparePromises: Array<Promise<?$ReadOnlyArray<PreparePushResult>>> =
     [];
   const notifications: Map<string, NotificationRow> = new Map();
   for (const userID in usersToCollapsableNotifInfo) {
     const threadInfos = _flow(
       _mapValues((serverThreadInfo: ServerThreadInfo) => {
         const rawThreadInfo = rawThreadInfoFromServerThreadInfo(
           serverThreadInfo,
           userID,
           { minimallyEncodePermissions: true },
         );
         if (!rawThreadInfo) {
           return null;
         }
         invariant(
           rawThreadInfo.minimallyEncoded,
           'rawThreadInfo from rawThreadInfoFromServerThreadInfo must be ' +
             'minimallyEncoded when minimallyEncodePermissions option is set',
         );
         return threadInfoFromRawThreadInfo(rawThreadInfo, userID, userInfos);
       }),
       _pickBy(threadInfo => threadInfo),
     )(serverThreadInfos);
     for (const notifInfo of usersToCollapsableNotifInfo[userID]) {
       preparePromises.push(
         preparePushNotif({
+          keyserverID,
           notifInfo,
           userID,
           pushUserInfo: pushInfo[userID],
           unreadCount: unreadCounts[userID],
           threadInfos,
           userInfos,
           dbIDs,
           rowsToSave: notifications,
         }),
       );
     }
   }
 
   const prepareResults = await Promise.all(preparePromises);
   const flattenedPrepareResults = prepareResults.filter(Boolean).flat();
 
   const deliveryResults = await deliverPushNotifsInEncryptionOrder(
     flattenedPrepareResults,
   );
   const cleanUpPromise = (async () => {
     if (dbIDs.length === 0) {
       return;
     }
     const query = SQL`DELETE FROM ids WHERE id IN (${dbIDs})`;
     await dbQuery(query);
   })();
 
   await Promise.all([
     cleanUpPromise,
     saveNotifResults(deliveryResults, notifications, true),
   ]);
 }
 
 type PreparePushResult = {
   +platform: Platform,
   +notificationInfo: NotificationInfo,
   +notification:
     | TargetedAPNsNotification
     | TargetedAndroidNotification
     | TargetedWebNotification
     | TargetedWNSNotification,
 };
 
 async function preparePushNotif(input: {
+  keyserverID: string,
   notifInfo: CollapsableNotifInfo,
   userID: string,
   pushUserInfo: PushUserInfo,
   unreadCount: number,
   threadInfos: {
     +[threadID: string]: ThreadInfo,
   },
   userInfos: { +[userID: string]: GlobalUserInfo },
   dbIDs: string[], // mutable
   rowsToSave: Map<string, NotificationRow>, // mutable
 }): Promise<?$ReadOnlyArray<PreparePushResult>> {
   const {
+    keyserverID,
     notifInfo,
     userID,
     pushUserInfo,
     unreadCount,
     threadInfos,
     userInfos,
     dbIDs,
     rowsToSave,
   } = input;
 
   const hydrateMessageInfo = (rawMessageInfo: RawMessageInfo) =>
     createMessageInfo(rawMessageInfo, userID, userInfos, threadInfos);
   const newMessageInfos = [];
   const newRawMessageInfos = [];
   for (const newRawMessageInfo of notifInfo.newMessageInfos) {
     const newMessageInfo = hydrateMessageInfo(newRawMessageInfo);
     if (newMessageInfo) {
       newMessageInfos.push(newMessageInfo);
       newRawMessageInfos.push(newRawMessageInfo);
     }
   }
   if (newMessageInfos.length === 0) {
     return null;
   }
   const existingMessageInfos = notifInfo.existingMessageInfos
     .map(hydrateMessageInfo)
     .filter(Boolean);
   const allMessageInfos = sortMessageInfoList([
     ...newMessageInfos,
     ...existingMessageInfos,
   ]);
   const [firstNewMessageInfo, ...remainingNewMessageInfos] = newMessageInfos;
   const { threadID } = firstNewMessageInfo;
 
   const threadInfo = threadInfos[threadID];
   const parentThreadInfo = threadInfo.parentThreadID
     ? threadInfos[threadInfo.parentThreadID]
     : null;
   const updateBadge = threadInfo.currentUser.subscription.home;
   const displayBanner = threadInfo.currentUser.subscription.pushNotifs;
   const username = userInfos[userID] && userInfos[userID].username;
 
   let resolvedUsername;
   if (getENSNames) {
     const userInfosWithENSNames = await getENSNames([userInfos[userID]]);
     resolvedUsername = userInfosWithENSNames[0].username;
   }
 
   const userWasMentioned =
     username &&
     threadInfo.currentUser.role &&
     oldValidUsernameRegex.test(username) &&
     newMessageInfos.some(newMessageInfo => {
       const unwrappedMessageInfo =
         newMessageInfo.type === messageTypes.SIDEBAR_SOURCE
           ? newMessageInfo.sourceMessage
           : newMessageInfo;
       return (
         unwrappedMessageInfo.type === messageTypes.TEXT &&
         (isUserMentioned(username, unwrappedMessageInfo.text) ||
           (resolvedUsername &&
             isUserMentioned(resolvedUsername, unwrappedMessageInfo.text)))
       );
     });
   if (!updateBadge && !displayBanner && !userWasMentioned) {
     return null;
   }
   const badgeOnly = !displayBanner && !userWasMentioned;
 
   const notifTargetUserInfo = { id: userID, username };
   const notifTexts = await notifTextsForMessageInfo(
     allMessageInfos,
     threadInfo,
     parentThreadInfo,
     notifTargetUserInfo,
     getENSNames,
   );
   if (!notifTexts) {
     return null;
   }
 
   const dbID = dbIDs.shift();
   invariant(dbID, 'should have sufficient DB IDs');
   const byPlatform = getDevicesByPlatform(pushUserInfo.devices);
   const firstMessageID = firstNewMessageInfo.id;
   invariant(firstMessageID, 'RawMessageInfo.id should be set on server');
   const notificationInfo = {
     source: 'new_message',
     dbID,
     userID,
     threadID,
     messageID: firstMessageID,
     collapseKey: notifInfo.collapseKey,
   };
 
   const preparePromises: Array<Promise<$ReadOnlyArray<PreparePushResult>>> = [];
 
   const iosVersionsToTokens = byPlatform.get('ios');
   if (iosVersionsToTokens) {
     for (const [versionKey, devices] of iosVersionsToTokens) {
       const { codeVersion, stateVersion } = stringToVersionKey(versionKey);
 
       const platformDetails: PlatformDetails = {
         platform: 'ios',
         codeVersion,
         stateVersion,
       };
       const shimmedNewRawMessageInfos = shimUnsupportedRawMessageInfos(
         newRawMessageInfos,
         platformDetails,
       );
       const preparePromise: Promise<$ReadOnlyArray<PreparePushResult>> =
         (async () => {
           const targetedNotifications = await prepareAPNsNotification(
             {
+              keyserverID,
               notifTexts,
               newRawMessageInfos: shimmedNewRawMessageInfos,
               threadID: threadInfo.id,
               collapseKey: notifInfo.collapseKey,
               badgeOnly,
               unreadCount,
               platformDetails,
             },
             devices,
           );
           return targetedNotifications.map(notification => ({
             notification,
             platform: 'ios',
             notificationInfo: {
               ...notificationInfo,
               codeVersion,
               stateVersion,
             },
           }));
         })();
       preparePromises.push(preparePromise);
     }
   }
   const androidVersionsToTokens = byPlatform.get('android');
   if (androidVersionsToTokens) {
     for (const [versionKey, devices] of androidVersionsToTokens) {
       const { codeVersion, stateVersion } = stringToVersionKey(versionKey);
       const platformDetails = {
         platform: 'android',
         codeVersion,
         stateVersion,
       };
       const shimmedNewRawMessageInfos = shimUnsupportedRawMessageInfos(
         newRawMessageInfos,
         platformDetails,
       );
       const preparePromise: Promise<$ReadOnlyArray<PreparePushResult>> =
         (async () => {
           const targetedNotifications = await prepareAndroidNotification(
             {
+              keyserverID,
               notifTexts,
               newRawMessageInfos: shimmedNewRawMessageInfos,
               threadID: threadInfo.id,
               collapseKey: notifInfo.collapseKey,
               badgeOnly,
               unreadCount,
               platformDetails,
               dbID,
             },
             devices,
           );
           return targetedNotifications.map(notification => ({
             notification,
             platform: 'android',
             notificationInfo: {
               ...notificationInfo,
               codeVersion,
               stateVersion,
             },
           }));
         })();
       preparePromises.push(preparePromise);
     }
   }
   const webVersionsToTokens = byPlatform.get('web');
   if (webVersionsToTokens) {
     for (const [versionKey, devices] of webVersionsToTokens) {
       const { codeVersion, stateVersion } = stringToVersionKey(versionKey);
       const platformDetails = {
         platform: 'web',
         codeVersion,
         stateVersion,
       };
 
       const preparePromise: Promise<$ReadOnlyArray<PreparePushResult>> =
         (async () => {
           const targetedNotifications = await prepareWebNotification(
             {
               notifTexts,
               threadID: threadInfo.id,
               unreadCount,
               platformDetails,
             },
             devices,
           );
 
           return targetedNotifications.map(notification => ({
             notification,
             platform: 'web',
             notificationInfo: {
               ...notificationInfo,
               codeVersion,
               stateVersion,
             },
           }));
         })();
       preparePromises.push(preparePromise);
     }
   }
   const macosVersionsToTokens = byPlatform.get('macos');
   if (macosVersionsToTokens) {
     for (const [versionKey, devices] of macosVersionsToTokens) {
       const { codeVersion, stateVersion, majorDesktopVersion } =
         stringToVersionKey(versionKey);
       const platformDetails = {
         platform: 'macos',
         codeVersion,
         stateVersion,
         majorDesktopVersion,
       };
       const shimmedNewRawMessageInfos = shimUnsupportedRawMessageInfos(
         newRawMessageInfos,
         platformDetails,
       );
       const preparePromise: Promise<$ReadOnlyArray<PreparePushResult>> =
         (async () => {
           const targetedNotifications = await prepareAPNsNotification(
             {
+              keyserverID,
               notifTexts,
               newRawMessageInfos: shimmedNewRawMessageInfos,
               threadID: threadInfo.id,
               collapseKey: notifInfo.collapseKey,
               badgeOnly,
               unreadCount,
               platformDetails,
             },
             devices,
           );
           return targetedNotifications.map(notification => ({
             notification,
             platform: 'macos',
             notificationInfo: {
               ...notificationInfo,
               codeVersion,
               stateVersion,
             },
           }));
         })();
       preparePromises.push(preparePromise);
     }
   }
   const windowsVersionsToTokens = byPlatform.get('windows');
   if (windowsVersionsToTokens) {
     for (const [versionKey, devices] of windowsVersionsToTokens) {
       const { codeVersion, stateVersion, majorDesktopVersion } =
         stringToVersionKey(versionKey);
       const platformDetails = {
         platform: 'windows',
         codeVersion,
         stateVersion,
         majorDesktopVersion,
       };
 
       const preparePromise: Promise<$ReadOnlyArray<PreparePushResult>> =
         (async () => {
           const targetedNotifications = await prepareWNSNotification(devices, {
             notifTexts,
             threadID: threadInfo.id,
             unreadCount,
             platformDetails,
           });
 
           return targetedNotifications.map(notification => ({
             notification,
             platform: 'windows',
             notificationInfo: {
               ...notificationInfo,
               codeVersion,
               stateVersion,
             },
           }));
         })();
       preparePromises.push(preparePromise);
     }
   }
 
   for (const newMessageInfo of remainingNewMessageInfos) {
     const newDBID = dbIDs.shift();
     invariant(newDBID, 'should have sufficient DB IDs');
     const messageID = newMessageInfo.id;
     invariant(messageID, 'RawMessageInfo.id should be set on server');
     rowsToSave.set(newDBID, {
       dbID: newDBID,
       userID,
       threadID: newMessageInfo.threadID,
       messageID,
       collapseKey: notifInfo.collapseKey,
       deliveries: [{ collapsedInto: dbID }],
     });
   }
 
   const prepareResults = await Promise.all(preparePromises);
   return prepareResults.flat();
 }
 
 // For better readability we don't differentiate between
 // encrypted and unencrypted notifs and order them together
 function compareEncryptionOrder(
   pushNotif1: PreparePushResult,
   pushNotif2: PreparePushResult,
 ): number {
   const order1 = pushNotif1.notification.encryptionOrder ?? 0;
   const order2 = pushNotif2.notification.encryptionOrder ?? 0;
   return order1 - order2;
 }
 
 async function deliverPushNotifsInEncryptionOrder(
   preparedPushNotifs: $ReadOnlyArray<PreparePushResult>,
 ): Promise<$ReadOnlyArray<PushResult>> {
   const deliveryPromises: Array<Promise<$ReadOnlyArray<PushResult>>> = [];
 
   const groupedByDevice = _groupBy(
     preparedPushNotif => preparedPushNotif.deviceToken,
   )(preparedPushNotifs);
 
   for (const preparedPushNotifsForDevice of values(groupedByDevice)) {
     const orderedPushNotifsForDevice = preparedPushNotifsForDevice.sort(
       compareEncryptionOrder,
     );
 
     const deviceDeliveryPromise = (async () => {
       const deliveries = [];
       for (const preparedPushNotif of orderedPushNotifsForDevice) {
         const { platform, notification, notificationInfo } = preparedPushNotif;
         let delivery: PushResult;
         if (platform === 'ios' || platform === 'macos') {
           delivery = await sendAPNsNotification(
             platform,
             [notification],
             notificationInfo,
           );
         } else if (platform === 'android') {
           delivery = await sendAndroidNotification(
             [notification],
             notificationInfo,
           );
         } else if (platform === 'web') {
           delivery = await sendWebNotifications(
             [notification],
             notificationInfo,
           );
         } else if (platform === 'windows') {
           delivery = await sendWNSNotification(
             [notification],
             notificationInfo,
           );
         }
         if (delivery) {
           deliveries.push(delivery);
         }
       }
       return deliveries;
     })();
     deliveryPromises.push(deviceDeliveryPromise);
   }
 
   const deliveryResults = await Promise.all(deliveryPromises);
   return deliveryResults.flat();
 }
 
 async function sendRescindNotifs(rescindInfo: PushInfo) {
   if (Object.keys(rescindInfo).length === 0) {
     return;
   }
 
   const usersToCollapsableNotifInfo = await fetchCollapsableNotifs(rescindInfo);
 
   const promises = [];
   for (const userID in usersToCollapsableNotifInfo) {
     for (const notifInfo of usersToCollapsableNotifInfo[userID]) {
       for (const existingMessageInfo of notifInfo.existingMessageInfos) {
         const rescindCondition = SQL`
           n.user = ${userID} AND
           n.thread = ${existingMessageInfo.threadID} AND
           n.message = ${existingMessageInfo.id}
         `;
 
         promises.push(rescindPushNotifs(rescindCondition));
       }
     }
   }
 
   await Promise.all(promises);
 }
 
 // The results in deliveryResults will be combined with the rows
 // in rowsToSave and then written to the notifications table
 async function saveNotifResults(
   deliveryResults: $ReadOnlyArray<PushResult>,
   inputRowsToSave: Map<string, NotificationRow>,
   rescindable: boolean,
 ) {
   const rowsToSave = new Map(inputRowsToSave);
 
   const allInvalidTokens = [];
   for (const deliveryResult of deliveryResults) {
     const { info, delivery, invalidTokens } = deliveryResult;
     const { dbID, userID } = info;
     const curNotifRow = rowsToSave.get(dbID);
     if (curNotifRow) {
       curNotifRow.deliveries.push(delivery);
     } else {
       // Ternary expressions for Flow
       const threadID = info.threadID ? info.threadID : null;
       const messageID = info.messageID ? info.messageID : null;
       const collapseKey = info.collapseKey ? info.collapseKey : null;
       rowsToSave.set(dbID, {
         dbID,
         userID,
         threadID,
         messageID,
         collapseKey,
         deliveries: [delivery],
       });
     }
     if (invalidTokens) {
       allInvalidTokens.push({
         userID,
         tokens: invalidTokens,
       });
     }
   }
 
   const notificationRows = [];
   for (const notification of rowsToSave.values()) {
     notificationRows.push([
       notification.dbID,
       notification.userID,
       notification.threadID,
       notification.messageID,
       notification.collapseKey,
       JSON.stringify(notification.deliveries),
       Number(!rescindable),
     ]);
   }
 
   const dbPromises: Array<Promise<mixed>> = [];
   if (allInvalidTokens.length > 0) {
     dbPromises.push(removeInvalidTokens(allInvalidTokens));
   }
   if (notificationRows.length > 0) {
     const query = SQL`
       INSERT INTO notifications
         (id, user, thread, message, collapse_key, delivery, rescinded)
       VALUES ${notificationRows}
     `;
     dbPromises.push(dbQuery(query));
   }
   if (dbPromises.length > 0) {
     await Promise.all(dbPromises);
   }
 }
 
 async function fetchInfos(pushInfo: PushInfo) {
   const usersToCollapsableNotifInfo = await fetchCollapsableNotifs(pushInfo);
 
   const threadIDs = new Set<string>();
   const threadWithChangedNamesToMessages = new Map<string, Array<string>>();
   const addThreadIDsFromMessageInfos = (rawMessageInfo: RawMessageInfo) => {
     const threadID = rawMessageInfo.threadID;
     threadIDs.add(threadID);
     const messageSpec = messageSpecs[rawMessageInfo.type];
     if (messageSpec.threadIDs) {
       for (const id of messageSpec.threadIDs(rawMessageInfo)) {
         threadIDs.add(id);
       }
     }
     if (
       rawMessageInfo.type === messageTypes.CHANGE_SETTINGS &&
       rawMessageInfo.field === 'name'
     ) {
       const messages = threadWithChangedNamesToMessages.get(threadID);
       if (messages) {
         messages.push(rawMessageInfo.id);
       } else {
         threadWithChangedNamesToMessages.set(threadID, [rawMessageInfo.id]);
       }
     }
   };
   for (const userID in usersToCollapsableNotifInfo) {
     for (const notifInfo of usersToCollapsableNotifInfo[userID]) {
       for (const rawMessageInfo of notifInfo.existingMessageInfos) {
         addThreadIDsFromMessageInfos(rawMessageInfo);
       }
       for (const rawMessageInfo of notifInfo.newMessageInfos) {
         addThreadIDsFromMessageInfos(rawMessageInfo);
       }
     }
   }
 
   // These threadInfos won't have currentUser set
   const threadPromise = fetchServerThreadInfos({ threadIDs });
 
   const oldNamesPromise: Promise<?QueryResults> = (async () => {
     if (threadWithChangedNamesToMessages.size === 0) {
       return undefined;
     }
     const typesThatAffectName = [
       messageTypes.CHANGE_SETTINGS,
       messageTypes.CREATE_THREAD,
     ];
     const oldNameQuery = SQL`
       SELECT IF(
         JSON_TYPE(JSON_EXTRACT(m.content, "$.name")) = 'NULL',
         "",
         JSON_UNQUOTE(JSON_EXTRACT(m.content, "$.name"))
       ) AS name, m.thread
       FROM (
         SELECT MAX(id) AS id
         FROM messages
         WHERE type IN (${typesThatAffectName})
           AND JSON_EXTRACT(content, "$.name") IS NOT NULL
           AND`;
     const threadClauses = [];
     for (const [threadID, messages] of threadWithChangedNamesToMessages) {
       threadClauses.push(
         SQL`(thread = ${threadID} AND id NOT IN (${messages}))`,
       );
     }
     oldNameQuery.append(mergeOrConditions(threadClauses));
     oldNameQuery.append(SQL`
         GROUP BY thread
       ) x
       LEFT JOIN messages m ON m.id = x.id
     `);
     return await dbQuery(oldNameQuery);
   })();
 
   const [threadResult, oldNames] = await Promise.all([
     threadPromise,
     oldNamesPromise,
   ]);
   const serverThreadInfos = { ...threadResult.threadInfos };
   if (oldNames) {
     const [result] = oldNames;
     for (const row of result) {
       const threadID = row.thread.toString();
       serverThreadInfos[threadID] = {
         ...serverThreadInfos[threadID],
         name: row.name,
       };
     }
   }
 
   const userInfos = await fetchNotifUserInfos(
     serverThreadInfos,
     usersToCollapsableNotifInfo,
   );
 
   return { usersToCollapsableNotifInfo, serverThreadInfos, userInfos };
 }
 
 async function fetchNotifUserInfos(
   serverThreadInfos: { +[threadID: string]: ServerThreadInfo },
   usersToCollapsableNotifInfo: { +[userID: string]: CollapsableNotifInfo[] },
 ) {
   const missingUserIDs = new Set<string>();
 
   for (const threadID in serverThreadInfos) {
     const serverThreadInfo = serverThreadInfos[threadID];
     for (const member of serverThreadInfo.members) {
       missingUserIDs.add(member.id);
     }
   }
 
   const addUserIDsFromMessageInfos = (rawMessageInfo: RawMessageInfo) => {
     missingUserIDs.add(rawMessageInfo.creatorID);
     const userIDs =
       messageSpecs[rawMessageInfo.type].userIDs?.(rawMessageInfo) ?? [];
     for (const userID of userIDs) {
       missingUserIDs.add(userID);
     }
   };
 
   for (const userID in usersToCollapsableNotifInfo) {
     missingUserIDs.add(userID);
     for (const notifInfo of usersToCollapsableNotifInfo[userID]) {
       for (const rawMessageInfo of notifInfo.existingMessageInfos) {
         addUserIDsFromMessageInfos(rawMessageInfo);
       }
       for (const rawMessageInfo of notifInfo.newMessageInfos) {
         addUserIDsFromMessageInfos(rawMessageInfo);
       }
     }
   }
 
   return await fetchUserInfos([...missingUserIDs]);
 }
 
 async function createDBIDs(pushInfo: PushInfo): Promise<string[]> {
   let numIDsNeeded = 0;
   for (const userID in pushInfo) {
     numIDsNeeded += pushInfo[userID].messageInfos.length;
   }
   return await createIDs('notifications', numIDsNeeded);
 }
 
 type VersionKey = {
   +codeVersion: number,
   +stateVersion: number,
   +majorDesktopVersion?: number,
 };
 const versionKeyRegex: RegExp = new RegExp(/^-?\d+\|-?\d+(\|-?\d+)?$/);
 function versionKeyToString(versionKey: VersionKey): string {
   const baseStringVersionKey = `${versionKey.codeVersion}|${versionKey.stateVersion}`;
   if (!versionKey.majorDesktopVersion) {
     return baseStringVersionKey;
   }
   return `${baseStringVersionKey}|${versionKey.majorDesktopVersion}`;
 }
 
 function stringToVersionKey(versionKeyString: string): VersionKey {
   invariant(
     versionKeyRegex.test(versionKeyString),
     'should pass correct version key string',
   );
   const [codeVersion, stateVersion, majorDesktopVersion] = versionKeyString
     .split('|')
     .map(Number);
   return { codeVersion, stateVersion, majorDesktopVersion };
 }
 
 function getDevicesByPlatform(
   devices: $ReadOnlyArray<Device>,
 ): Map<Platform, Map<string, Array<NotificationTargetDevice>>> {
   const byPlatform = new Map<
     Platform,
     Map<string, Array<NotificationTargetDevice>>,
   >();
   for (const device of devices) {
     let innerMap = byPlatform.get(device.platform);
     if (!innerMap) {
       innerMap = new Map<string, Array<NotificationTargetDevice>>();
       byPlatform.set(device.platform, innerMap);
     }
     const codeVersion: number =
       device.codeVersion !== null && device.codeVersion !== undefined
         ? device.codeVersion
         : -1;
     const stateVersion: number = device.stateVersion ?? -1;
 
     let versionsObject = { codeVersion, stateVersion };
     if (device.majorDesktopVersion) {
       versionsObject = {
         ...versionsObject,
         majorDesktopVersion: device.majorDesktopVersion,
       };
     }
 
     const versionKey = versionKeyToString(versionsObject);
     let innerMostArrayTmp: ?Array<NotificationTargetDevice> =
       innerMap.get(versionKey);
     if (!innerMostArrayTmp) {
       innerMostArrayTmp = [];
       innerMap.set(versionKey, innerMostArrayTmp);
     }
     const innerMostArray = innerMostArrayTmp;
 
     innerMostArray.push({
       cookieID: device.cookieID,
       deviceToken: device.deviceToken,
     });
   }
   return byPlatform;
 }
 
 type APNsNotifInputData = {
+  +keyserverID: string,
   +notifTexts: ResolvedNotifTexts,
   +newRawMessageInfos: RawMessageInfo[],
   +threadID: string,
   +collapseKey: ?string,
   +badgeOnly: boolean,
   +unreadCount: number,
   +platformDetails: PlatformDetails,
 };
 const apnsNotifInputDataValidator = tShape<APNsNotifInputData>({
+  keyserverID: t.String,
   notifTexts: resolvedNotifTextsValidator,
   newRawMessageInfos: t.list(rawMessageInfoValidator),
   threadID: tID,
   collapseKey: t.maybe(t.String),
   badgeOnly: t.Boolean,
   unreadCount: t.Number,
   platformDetails: tPlatformDetails,
 });
 async function prepareAPNsNotification(
   inputData: APNsNotifInputData,
   devices: $ReadOnlyArray<NotificationTargetDevice>,
 ): Promise<$ReadOnlyArray<TargetedAPNsNotification>> {
   const convertedData = await validateOutput(
     inputData.platformDetails,
     apnsNotifInputDataValidator,
     inputData,
   );
   const {
+    keyserverID,
     notifTexts,
     newRawMessageInfos,
     threadID,
     collapseKey,
     badgeOnly,
     unreadCount,
     platformDetails,
   } = convertedData;
 
   const canDecryptNonCollapsibleTextIOSNotifs =
     platformDetails.codeVersion && platformDetails.codeVersion > 222;
 
   const isNonCollapsibleTextNotification =
     newRawMessageInfos.every(
       newRawMessageInfo => newRawMessageInfo.type === messageTypes.TEXT,
     ) && !collapseKey;
 
   const canDecryptAllIOSNotifs =
     platformDetails.codeVersion && platformDetails.codeVersion >= 267;
 
   const canDecryptIOSNotif =
     platformDetails.platform === 'ios' &&
     (canDecryptAllIOSNotifs ||
       (isNonCollapsibleTextNotification &&
         canDecryptNonCollapsibleTextIOSNotifs));
 
   const canDecryptMacOSNotifs =
     platformDetails.platform === 'macos' &&
     hasMinCodeVersion(platformDetails, {
       web: 47,
       majorDesktop: 9,
     });
 
   const shouldBeEncrypted = canDecryptIOSNotif || canDecryptMacOSNotifs;
 
   const uniqueID = uuidv4();
   const notification = new apn.Notification();
   notification.topic = getAPNsNotificationTopic(platformDetails);
 
   const { merged, ...rest } = notifTexts;
   // We don't include alert's body on macos because we
   // handle displaying the notification ourselves and
   // we don't want macOS to display it automatically.
   if (!badgeOnly && platformDetails.platform !== 'macos') {
     notification.body = merged;
     notification.sound = 'default';
   }
+
   notification.payload = {
     ...notification.payload,
     ...rest,
   };
+  if (platformDetails.platform !== 'macos') {
+    notification.payload.keyserverID = keyserverID;
+  }
 
   notification.badge = unreadCount;
   notification.threadId = threadID;
   notification.id = uniqueID;
   notification.pushType = 'alert';
   notification.payload.id = uniqueID;
   notification.payload.threadID = threadID;
 
   if (platformDetails.codeVersion && platformDetails.codeVersion > 198) {
     notification.mutableContent = true;
   }
   if (collapseKey && (canDecryptAllIOSNotifs || canDecryptMacOSNotifs)) {
     notification.payload.collapseID = collapseKey;
   } else if (collapseKey) {
     notification.collapseId = collapseKey;
   }
   const messageInfos = JSON.stringify(newRawMessageInfos);
   // We make a copy before checking notification's length, because calling
   // length compiles the notification and makes it immutable. Further
   // changes to its properties won't be reflected in the final plaintext
   // data that is sent.
   const copyWithMessageInfos = _cloneDeep(notification);
   copyWithMessageInfos.payload = {
     ...copyWithMessageInfos.payload,
     messageInfos,
   };
 
   const notificationSizeValidator = (notif: apn.Notification) =>
     notif.length() <= apnMaxNotificationPayloadByteSize;
 
   if (!shouldBeEncrypted) {
     const notificationToSend = notificationSizeValidator(
       _cloneDeep(copyWithMessageInfos),
     )
       ? copyWithMessageInfos
       : notification;
     return devices.map(({ deviceToken }) => ({
       notification: notificationToSend,
       deviceToken,
     }));
   }
 
   const notifsWithMessageInfos = await prepareEncryptedAPNsNotifications(
     devices,
     copyWithMessageInfos,
     platformDetails.codeVersion,
     notificationSizeValidator,
   );
 
   const devicesWithExcessiveSize = notifsWithMessageInfos
     .filter(({ payloadSizeExceeded }) => payloadSizeExceeded)
     .map(({ deviceToken, cookieID }) => ({ deviceToken, cookieID }));
 
   if (devicesWithExcessiveSize.length === 0) {
     return notifsWithMessageInfos.map(
       ({
         notification: notif,
         deviceToken,
         encryptedPayloadHash,
         encryptionOrder,
       }) => ({
         notification: notif,
         deviceToken,
         encryptedPayloadHash,
         encryptionOrder,
       }),
     );
   }
 
   const notifsWithoutMessageInfos = await prepareEncryptedAPNsNotifications(
     devicesWithExcessiveSize,
     notification,
     platformDetails.codeVersion,
   );
 
   const targetedNotifsWithMessageInfos = notifsWithMessageInfos
     .filter(({ payloadSizeExceeded }) => !payloadSizeExceeded)
     .map(
       ({
         notification: notif,
         deviceToken,
         encryptedPayloadHash,
         encryptionOrder,
       }) => ({
         notification: notif,
         deviceToken,
         encryptedPayloadHash,
         encryptionOrder,
       }),
     );
 
   const targetedNotifsWithoutMessageInfos = notifsWithoutMessageInfos.map(
     ({
       notification: notif,
       deviceToken,
       encryptedPayloadHash,
       encryptionOrder,
     }) => ({
       notification: notif,
       deviceToken,
       encryptedPayloadHash,
       encryptionOrder,
     }),
   );
 
   return [
     ...targetedNotifsWithMessageInfos,
     ...targetedNotifsWithoutMessageInfos,
   ];
 }
 
 type AndroidNotifInputData = {
   ...APNsNotifInputData,
   +dbID: string,
 };
 const androidNotifInputDataValidator = tShape<AndroidNotifInputData>({
   ...apnsNotifInputDataValidator.meta.props,
   dbID: t.String,
 });
 async function prepareAndroidNotification(
   inputData: AndroidNotifInputData,
   devices: $ReadOnlyArray<NotificationTargetDevice>,
 ): Promise<$ReadOnlyArray<TargetedAndroidNotification>> {
   const convertedData = await validateOutput(
     inputData.platformDetails,
     androidNotifInputDataValidator,
     inputData,
   );
   const {
+    keyserverID,
     notifTexts,
     newRawMessageInfos,
     threadID,
     collapseKey,
     badgeOnly,
     unreadCount,
     platformDetails: { codeVersion },
     dbID,
   } = convertedData;
   const canDecryptNonCollapsibleTextNotifs = codeVersion && codeVersion > 228;
 
   const isNonCollapsibleTextNotif =
     newRawMessageInfos.every(
       newRawMessageInfo => newRawMessageInfo.type === messageTypes.TEXT,
     ) && !collapseKey;
 
   const canDecryptAllNotifTypes = codeVersion && codeVersion >= 267;
 
   const shouldBeEncrypted =
     canDecryptAllNotifTypes ||
     (canDecryptNonCollapsibleTextNotifs && isNonCollapsibleTextNotif);
 
   const { merged, ...rest } = notifTexts;
   const notification = {
     data: {
+      keyserverID,
       badge: unreadCount.toString(),
       ...rest,
       threadID,
     },
   };
 
   let notifID;
   if (collapseKey && canDecryptAllNotifTypes) {
     notifID = dbID;
     notification.data = {
       ...notification.data,
       collapseKey,
     };
   } else if (collapseKey) {
     notifID = collapseKey;
   } else {
     notifID = dbID;
   }
 
   // The reason we only include `badgeOnly` for newer clients is because older
   // clients don't know how to parse it. The reason we only include `id` for
   // newer clients is that if the older clients see that field, they assume
   // the notif has a full payload, and then crash when trying to parse it.
   // By skipping `id` we allow old clients to still handle in-app notifs and
   // badge updating.
   if (!badgeOnly || (codeVersion && codeVersion >= 69)) {
     notification.data = {
       ...notification.data,
       id: notifID,
       badgeOnly: badgeOnly ? '1' : '0',
     };
   }
 
   const messageInfos = JSON.stringify(newRawMessageInfos);
   const copyWithMessageInfos = {
     ...notification,
     data: { ...notification.data, messageInfos },
   };
 
   if (!shouldBeEncrypted) {
     const notificationToSend =
       Buffer.byteLength(JSON.stringify(copyWithMessageInfos)) <=
       fcmMaxNotificationPayloadByteSize
         ? copyWithMessageInfos
         : notification;
 
     return devices.map(({ deviceToken }) => ({
       notification: notificationToSend,
       deviceToken,
     }));
   }
 
   const notificationsSizeValidator = (notif: AndroidNotification) => {
     const serializedNotif = JSON.stringify(notif);
     return (
       !serializedNotif ||
       Buffer.byteLength(serializedNotif) <= fcmMaxNotificationPayloadByteSize
     );
   };
 
   const notifsWithMessageInfos = await prepareEncryptedAndroidNotifications(
     devices,
     copyWithMessageInfos,
     notificationsSizeValidator,
   );
 
   const devicesWithExcessiveSize = notifsWithMessageInfos
     .filter(({ payloadSizeExceeded }) => payloadSizeExceeded)
     .map(({ cookieID, deviceToken }) => ({ cookieID, deviceToken }));
 
   if (devicesWithExcessiveSize.length === 0) {
     return notifsWithMessageInfos.map(
       ({ notification: notif, deviceToken, encryptionOrder }) => ({
         notification: notif,
         deviceToken,
         encryptionOrder,
       }),
     );
   }
 
   const notifsWithoutMessageInfos = await prepareEncryptedAndroidNotifications(
     devicesWithExcessiveSize,
     notification,
   );
 
   const targetedNotifsWithMessageInfos = notifsWithMessageInfos
     .filter(({ payloadSizeExceeded }) => !payloadSizeExceeded)
     .map(({ notification: notif, deviceToken, encryptionOrder }) => ({
       notification: notif,
       deviceToken,
       encryptionOrder,
     }));
 
   const targetedNotifsWithoutMessageInfos = notifsWithoutMessageInfos.map(
     ({ notification: notif, deviceToken, encryptionOrder }) => ({
       notification: notif,
       deviceToken,
       encryptionOrder,
     }),
   );
 
   return [
     ...targetedNotifsWithMessageInfos,
     ...targetedNotifsWithoutMessageInfos,
   ];
 }
 
 type WebNotifInputData = {
   +notifTexts: ResolvedNotifTexts,
   +threadID: string,
   +unreadCount: number,
   +platformDetails: PlatformDetails,
 };
 const webNotifInputDataValidator = tShape<WebNotifInputData>({
   notifTexts: resolvedNotifTextsValidator,
   threadID: tID,
   unreadCount: t.Number,
   platformDetails: tPlatformDetails,
 });
 async function prepareWebNotification(
   inputData: WebNotifInputData,
   devices: $ReadOnlyArray<NotificationTargetDevice>,
 ): Promise<$ReadOnlyArray<TargetedWebNotification>> {
   const convertedData = await validateOutput(
     inputData.platformDetails,
     webNotifInputDataValidator,
     inputData,
   );
   const { notifTexts, threadID, unreadCount } = convertedData;
   const id = uuidv4();
   const { merged, ...rest } = notifTexts;
   const notification = {
     ...rest,
     unreadCount,
     id,
     threadID,
   };
 
   const shouldBeEncrypted = hasMinCodeVersion(convertedData.platformDetails, {
     web: 43,
   });
 
   if (!shouldBeEncrypted) {
     return devices.map(({ deviceToken }) => ({ deviceToken, notification }));
   }
 
   return prepareEncryptedWebNotifications(devices, notification);
 }
 
 type WNSNotifInputData = {
   +notifTexts: ResolvedNotifTexts,
   +threadID: string,
   +unreadCount: number,
   +platformDetails: PlatformDetails,
 };
 const wnsNotifInputDataValidator = tShape<WNSNotifInputData>({
   notifTexts: resolvedNotifTextsValidator,
   threadID: tID,
   unreadCount: t.Number,
   platformDetails: tPlatformDetails,
 });
 async function prepareWNSNotification(
   devices: $ReadOnlyArray<NotificationTargetDevice>,
   inputData: WNSNotifInputData,
 ): Promise<$ReadOnlyArray<TargetedWNSNotification>> {
   const convertedData = await validateOutput(
     inputData.platformDetails,
     wnsNotifInputDataValidator,
     inputData,
   );
   const { notifTexts, threadID, unreadCount } = convertedData;
   const { merged, ...rest } = notifTexts;
   const notification = {
     ...rest,
     unreadCount,
     threadID,
   };
 
   if (
     Buffer.byteLength(JSON.stringify(notification)) >
     wnsMaxNotificationPayloadByteSize
   ) {
     console.warn('WNS notification exceeds size limit');
   }
 
   const shouldBeEncrypted = hasMinCodeVersion(inputData.platformDetails, {
     majorDesktop: 10,
   });
 
   if (!shouldBeEncrypted) {
     return devices.map(({ deviceToken }) => ({
       deviceToken,
       notification,
     }));
   }
   return await prepareEncryptedWNSNotifications(devices, notification);
 }
 
 type NotificationInfo =
   | {
       +source: 'new_message',
       +dbID: string,
       +userID: string,
       +threadID: string,
       +messageID: string,
       +collapseKey: ?string,
       +codeVersion: number,
       +stateVersion: number,
     }
   | {
       +source: 'mark_as_unread' | 'mark_as_read' | 'activity_update',
       +dbID: string,
       +userID: string,
       +codeVersion: number,
       +stateVersion: number,
     };
 
 type APNsDelivery = {
   +source: $PropertyType<NotificationInfo, 'source'>,
   +deviceType: 'ios' | 'macos',
   +iosID: string,
   +deviceTokens: $ReadOnlyArray<string>,
   +codeVersion: number,
   +stateVersion: number,
   +errors?: $ReadOnlyArray<ResponseFailure>,
   +encryptedPayloadHashes?: $ReadOnlyArray<string>,
   +deviceTokensToPayloadHash?: {
     +[deviceToken: string]: string,
   },
 };
 type APNsResult = {
   info: NotificationInfo,
   delivery: APNsDelivery,
   invalidTokens?: $ReadOnlyArray<string>,
 };
 async function sendAPNsNotification(
   platform: 'ios' | 'macos',
   targetedNotifications: $ReadOnlyArray<TargetedAPNsNotification>,
   notificationInfo: NotificationInfo,
 ): Promise<APNsResult> {
   const { source, codeVersion, stateVersion } = notificationInfo;
 
   const response = await apnPush({
     targetedNotifications,
     platformDetails: { platform, codeVersion },
   });
   invariant(
     new Set(targetedNotifications.map(({ notification }) => notification.id))
       .size === 1,
     'Encrypted versions of the same notification must share id value',
   );
   const iosID = targetedNotifications[0].notification.id;
   const deviceTokens = targetedNotifications.map(
     ({ deviceToken }) => deviceToken,
   );
   let delivery: APNsDelivery = {
     source,
     deviceType: platform,
     iosID,
     deviceTokens,
     codeVersion,
     stateVersion,
   };
   if (response.errors) {
     delivery = {
       ...delivery,
       errors: response.errors,
     };
   }
 
   const deviceTokensToPayloadHash: { [string]: string } = {};
   for (const targetedNotification of targetedNotifications) {
     if (targetedNotification.encryptedPayloadHash) {
       deviceTokensToPayloadHash[targetedNotification.deviceToken] =
         targetedNotification.encryptedPayloadHash;
     }
   }
   if (Object.keys(deviceTokensToPayloadHash).length !== 0) {
     delivery = {
       ...delivery,
       deviceTokensToPayloadHash,
     };
   }
 
   const result: APNsResult = {
     info: notificationInfo,
     delivery,
   };
   if (response.invalidTokens) {
     result.invalidTokens = response.invalidTokens;
   }
   return result;
 }
 
 type PushResult = AndroidResult | APNsResult | WebResult | WNSResult;
 type PushDelivery = AndroidDelivery | APNsDelivery | WebDelivery | WNSDelivery;
 type AndroidDelivery = {
   source: $PropertyType<NotificationInfo, 'source'>,
   deviceType: 'android',
   androidIDs: $ReadOnlyArray<string>,
   deviceTokens: $ReadOnlyArray<string>,
   codeVersion: number,
   stateVersion: number,
   errors?: $ReadOnlyArray<Object>,
 };
 type AndroidResult = {
   info: NotificationInfo,
   delivery: AndroidDelivery,
   invalidTokens?: $ReadOnlyArray<string>,
 };
 async function sendAndroidNotification(
   targetedNotifications: $ReadOnlyArray<TargetedAndroidNotification>,
   notificationInfo: NotificationInfo,
 ): Promise<AndroidResult> {
   const collapseKey = notificationInfo.collapseKey
     ? notificationInfo.collapseKey
     : null; // for Flow...
   const { source, codeVersion, stateVersion } = notificationInfo;
   const response = await fcmPush({
     targetedNotifications,
     collapseKey,
     codeVersion,
   });
   const deviceTokens = targetedNotifications.map(
     ({ deviceToken }) => deviceToken,
   );
   const androidIDs = response.fcmIDs ? response.fcmIDs : [];
   const delivery: AndroidDelivery = {
     source,
     deviceType: 'android',
     androidIDs,
     deviceTokens,
     codeVersion,
     stateVersion,
   };
   if (response.errors) {
     delivery.errors = response.errors;
   }
   const result: AndroidResult = {
     info: notificationInfo,
     delivery,
   };
   if (response.invalidTokens) {
     result.invalidTokens = response.invalidTokens;
   }
   return result;
 }
 
 type WebDelivery = {
   +source: $PropertyType<NotificationInfo, 'source'>,
   +deviceType: 'web',
   +deviceTokens: $ReadOnlyArray<string>,
   +codeVersion?: number,
   +stateVersion: number,
   +errors?: $ReadOnlyArray<WebPushError>,
 };
 type WebResult = {
   +info: NotificationInfo,
   +delivery: WebDelivery,
   +invalidTokens?: $ReadOnlyArray<string>,
 };
 async function sendWebNotifications(
   targetedNotifications: $ReadOnlyArray<TargetedWebNotification>,
   notificationInfo: NotificationInfo,
 ): Promise<WebResult> {
   const { source, codeVersion, stateVersion } = notificationInfo;
 
   const response = await webPush(targetedNotifications);
 
   const deviceTokens = targetedNotifications.map(
     ({ deviceToken }) => deviceToken,
   );
   const delivery: WebDelivery = {
     source,
     deviceType: 'web',
     deviceTokens,
     codeVersion,
     errors: response.errors,
     stateVersion,
   };
   const result: WebResult = {
     info: notificationInfo,
     delivery,
     invalidTokens: response.invalidTokens,
   };
   return result;
 }
 
 type WNSDelivery = {
   +source: $PropertyType<NotificationInfo, 'source'>,
   +deviceType: 'windows',
   +wnsIDs: $ReadOnlyArray<string>,
   +deviceTokens: $ReadOnlyArray<string>,
   +codeVersion?: number,
   +stateVersion: number,
   +errors?: $ReadOnlyArray<WNSPushError>,
 };
 type WNSResult = {
   +info: NotificationInfo,
   +delivery: WNSDelivery,
   +invalidTokens?: $ReadOnlyArray<string>,
 };
 async function sendWNSNotification(
   targetedNotifications: $ReadOnlyArray<TargetedWNSNotification>,
   notificationInfo: NotificationInfo,
 ): Promise<WNSResult> {
   const { source, codeVersion, stateVersion } = notificationInfo;
 
   const response = await wnsPush(targetedNotifications);
 
   const deviceTokens = targetedNotifications.map(
     ({ deviceToken }) => deviceToken,
   );
   const wnsIDs = response.wnsIDs ?? [];
   const delivery: WNSDelivery = {
     source,
     deviceType: 'windows',
     wnsIDs,
     deviceTokens,
     codeVersion,
     errors: response.errors,
     stateVersion,
   };
   const result: WNSResult = {
     info: notificationInfo,
     delivery,
     invalidTokens: response.invalidTokens,
   };
   return result;
 }
 
 type InvalidToken = {
   +userID: string,
   +tokens: $ReadOnlyArray<string>,
 };
 async function removeInvalidTokens(
   invalidTokens: $ReadOnlyArray<InvalidToken>,
 ): Promise<void> {
   const sqlTuples = invalidTokens.map(
     invalidTokenUser =>
       SQL`(
       user = ${invalidTokenUser.userID} AND
       device_token IN (${invalidTokenUser.tokens})
     )`,
   );
   const sqlCondition = mergeOrConditions(sqlTuples);
 
   const selectQuery = SQL`
     SELECT id, user, device_token
     FROM cookies
     WHERE
   `;
   selectQuery.append(sqlCondition);
   const [result] = await dbQuery(selectQuery);
 
   const userCookiePairsToInvalidDeviceTokens = new Map<string, Set<string>>();
   for (const row of result) {
     const userCookiePair = `${row.user}|${row.id}`;
     const existing = userCookiePairsToInvalidDeviceTokens.get(userCookiePair);
     if (existing) {
       existing.add(row.device_token);
     } else {
       userCookiePairsToInvalidDeviceTokens.set(
         userCookiePair,
         new Set([row.device_token]),
       );
     }
   }
 
   const time = Date.now();
   const promises: Array<Promise<mixed>> = [];
   for (const entry of userCookiePairsToInvalidDeviceTokens) {
     const [userCookiePair, deviceTokens] = entry;
     const [userID, cookieID] = userCookiePair.split('|');
     const updateDatas = [...deviceTokens].map(deviceToken => ({
       type: updateTypes.BAD_DEVICE_TOKEN,
       userID,
       time,
       deviceToken,
       targetCookie: cookieID,
     }));
     promises.push(createUpdates(updateDatas));
   }
 
   const updateQuery = SQL`
     UPDATE cookies
     SET device_token = NULL
     WHERE
   `;
   updateQuery.append(sqlCondition);
   promises.push(dbQuery(updateQuery));
 
   await Promise.all(promises);
 }
 
 async function updateBadgeCount(
   viewer: Viewer,
   source: 'mark_as_unread' | 'mark_as_read' | 'activity_update',
 ) {
   const { userID } = viewer;
 
   const deviceTokenQuery = SQL`
     SELECT platform, device_token, versions, id
     FROM cookies
     WHERE user = ${userID}
       AND device_token IS NOT NULL
   `;
   if (viewer.data.cookieID) {
     deviceTokenQuery.append(SQL`AND id != ${viewer.cookieID} `);
   }
-  const [unreadCounts, [deviceTokenResult], [dbID]] = await Promise.all([
-    getUnreadCounts([userID]),
-    dbQuery(deviceTokenQuery),
-    createIDs('notifications', 1),
-  ]);
+  const [unreadCounts, [deviceTokenResult], [dbID], keyserverID] =
+    await Promise.all([
+      getUnreadCounts([userID]),
+      dbQuery(deviceTokenQuery),
+      createIDs('notifications', 1),
+      thisKeyserverID(),
+    ]);
   const unreadCount = unreadCounts[userID];
   const devices = deviceTokenResult.map(row => {
     const versions = JSON.parse(row.versions);
     return {
       platform: row.platform,
       cookieID: row.id,
       deviceToken: row.device_token,
       codeVersion: versions?.codeVersion,
       stateVersion: versions?.stateVersion,
     };
   });
   const byPlatform = getDevicesByPlatform(devices);
 
   const preparePromises: Array<Promise<$ReadOnlyArray<PreparePushResult>>> = [];
 
   const iosVersionsToTokens = byPlatform.get('ios');
   if (iosVersionsToTokens) {
     for (const [versionKey, deviceInfos] of iosVersionsToTokens) {
       const { codeVersion, stateVersion } = stringToVersionKey(versionKey);
       const notification = new apn.Notification();
       notification.topic = getAPNsNotificationTopic({
         platform: 'ios',
         codeVersion,
         stateVersion,
       });
       notification.badge = unreadCount;
       notification.pushType = 'alert';
+      notification.payload.keyserverID = keyserverID;
       const preparePromise: Promise<PreparePushResult[]> = (async () => {
         let targetedNotifications: $ReadOnlyArray<TargetedAPNsNotification>;
         if (codeVersion > 222) {
           const notificationsArray = await prepareEncryptedAPNsNotifications(
             deviceInfos,
             notification,
             codeVersion,
           );
           targetedNotifications = notificationsArray.map(
             ({ notification: notif, deviceToken, encryptionOrder }) => ({
               notification: notif,
               deviceToken,
               encryptionOrder,
             }),
           );
         } else {
           targetedNotifications = deviceInfos.map(({ deviceToken }) => ({
             notification,
             deviceToken,
           }));
         }
         return targetedNotifications.map(targetedNotification => ({
           notification: targetedNotification,
           platform: 'ios',
           notificationInfo: {
             source,
             dbID,
             userID,
             codeVersion,
             stateVersion,
           },
         }));
       })();
 
       preparePromises.push(preparePromise);
     }
   }
 
   const androidVersionsToTokens = byPlatform.get('android');
   if (androidVersionsToTokens) {
     for (const [versionKey, deviceInfos] of androidVersionsToTokens) {
       const { codeVersion, stateVersion } = stringToVersionKey(versionKey);
       const notificationData =
         codeVersion < 69
           ? { badge: unreadCount.toString() }
           : { badge: unreadCount.toString(), badgeOnly: '1' };
-      const notification = { data: notificationData };
+      const notification = {
+        data: { ...notificationData, keyserverID },
+      };
       const preparePromise: Promise<PreparePushResult[]> = (async () => {
         let targetedNotifications: $ReadOnlyArray<TargetedAndroidNotification>;
         if (codeVersion > 222) {
           const notificationsArray = await prepareEncryptedAndroidNotifications(
             deviceInfos,
             notification,
           );
           targetedNotifications = notificationsArray.map(
             ({ notification: notif, deviceToken, encryptionOrder }) => ({
               notification: notif,
               deviceToken,
               encryptionOrder,
             }),
           );
         } else {
           targetedNotifications = deviceInfos.map(({ deviceToken }) => ({
             deviceToken,
             notification,
           }));
         }
         return targetedNotifications.map(targetedNotification => ({
           notification: targetedNotification,
           platform: 'android',
           notificationInfo: {
             source,
             dbID,
             userID,
             codeVersion,
             stateVersion,
           },
         }));
       })();
       preparePromises.push(preparePromise);
     }
   }
 
   const macosVersionsToTokens = byPlatform.get('macos');
   if (macosVersionsToTokens) {
     for (const [versionKey, deviceInfos] of macosVersionsToTokens) {
       const { codeVersion, stateVersion, majorDesktopVersion } =
         stringToVersionKey(versionKey);
       const notification = new apn.Notification();
       notification.topic = getAPNsNotificationTopic({
         platform: 'macos',
         codeVersion,
         stateVersion,
         majorDesktopVersion,
       });
       notification.badge = unreadCount;
       notification.pushType = 'alert';
       const preparePromise: Promise<PreparePushResult[]> = (async () => {
         const shouldBeEncrypted = hasMinCodeVersion(viewer.platformDetails, {
           web: 47,
           majorDesktop: 9,
         });
         let targetedNotifications: $ReadOnlyArray<TargetedAPNsNotification>;
         if (shouldBeEncrypted) {
           const notificationsArray = await prepareEncryptedAPNsNotifications(
             deviceInfos,
             notification,
             codeVersion,
           );
           targetedNotifications = notificationsArray.map(
             ({ notification: notif, deviceToken, encryptionOrder }) => ({
               notification: notif,
               deviceToken,
               encryptionOrder,
             }),
           );
         } else {
           targetedNotifications = deviceInfos.map(({ deviceToken }) => ({
             deviceToken,
             notification,
           }));
         }
 
         return targetedNotifications.map(targetedNotification => ({
           notification: targetedNotification,
           platform: 'macos',
           notificationInfo: {
             source,
             dbID,
             userID,
             codeVersion,
             stateVersion,
           },
         }));
       })();
       preparePromises.push(preparePromise);
     }
   }
 
   const prepareResults = await Promise.all(preparePromises);
   const flattenedPrepareResults = prepareResults.filter(Boolean).flat();
   const deliveryResults = await deliverPushNotifsInEncryptionOrder(
     flattenedPrepareResults,
   );
   await saveNotifResults(deliveryResults, new Map(), false);
 }
 
 export { sendPushNotifs, sendRescindNotifs, updateBadgeCount };
diff --git a/keyserver/src/push/types.js b/keyserver/src/push/types.js
index 195bb6a3d..7ed3a3e76 100644
--- a/keyserver/src/push/types.js
+++ b/keyserver/src/push/types.js
@@ -1,80 +1,84 @@
 // @flow
 
 import apn from '@parse/node-apn';
 
 import type {
   WebNotification,
   WNSNotification,
 } from 'lib/types/notif-types.js';
 
 export type TargetedAPNsNotification = {
   +notification: apn.Notification,
   +deviceToken: string,
   +encryptedPayloadHash?: string,
   +encryptionOrder?: number,
 };
 
 type AndroidNotificationPayloadBase = {
   +badge: string,
   +body?: string,
   +title?: string,
   +prefix?: string,
   +threadID?: string,
   +collapseKey?: string,
   +encryptionFailed?: '1',
 };
 
 export type AndroidNotificationPayload =
   | {
       ...AndroidNotificationPayloadBase,
       +messageInfos?: string,
     }
   | {
       ...AndroidNotificationPayloadBase,
       +blobHash: string,
       +encryptionKey: string,
     };
 
 export type AndroidNotification = {
   +data: {
     +id?: string,
     +badgeOnly?: string,
+    +keyserverID: string,
     ...AndroidNotificationPayload | { +encryptedPayload: string },
   },
 };
 
 export type AndroidNotificationRescind = {
-  +data:
-    | {
-        +badge: string,
-        +rescind: 'true',
-        +rescindID: string,
-        +setUnreadStatus: 'true',
-        +threadID: string,
-        +encryptionFailed?: string,
-      }
-    | { +encryptedPayload: string },
+  +data: {
+    +keyserverID: string,
+    ...
+      | {
+          +badge: string,
+          +rescind: 'true',
+          +rescindID: string,
+          +setUnreadStatus: 'true',
+          +threadID: string,
+          +encryptionFailed?: string,
+        }
+      | { +encryptedPayload: string },
+  },
 };
 
 export type TargetedAndroidNotification = {
   +notification: AndroidNotification | AndroidNotificationRescind,
   +deviceToken: string,
   +encryptionOrder?: number,
 };
 
 export type TargetedWebNotification = {
   +notification: WebNotification,
   +deviceToken: string,
   +encryptionOrder?: number,
 };
 
 export type TargetedWNSNotification = {
   +notification: WNSNotification,
   +deviceToken: string,
   +encryptionOrder?: number,
 };
 
 export type NotificationTargetDevice = {
   +cookieID: string,
   +deviceToken: string,
 };