diff --git a/keyserver/src/push/crypto.js b/keyserver/src/push/crypto.js
--- a/keyserver/src/push/crypto.js
+++ b/keyserver/src/push/crypto.js
@@ -11,13 +11,18 @@
   NotificationTargetDevice,
 } from './types.js';
 import { encryptAndUpdateOlmSession } from '../updaters/olm-session-updater.js';
+import { getOlmUtility } from '../utils/olm-utils.js';
 
 async function encryptIOSNotification(
   cookieID: string,
   notification: apn.Notification,
   codeVersion?: ?number,
   notificationSizeValidator?: apn.Notification => boolean,
-): Promise<{ +notification: apn.Notification, +payloadSizeExceeded: boolean }> {
+): Promise<{
+  +notification: apn.Notification,
+  +payloadSizeExceeded: boolean,
+  +encryptedPayloadHash?: string,
+}> {
   invariant(
     !notification.collapseId,
     'Collapsible notifications encryption currently not implemented',
@@ -71,9 +76,11 @@
       };
     }
 
+    const encryptedPayloadHash = getOlmUtility().sha256(serializedPayload.body);
     return {
       notification: encryptedNotification,
       payloadSizeExceeded: !!dbPersistConditionViolated,
+      encryptedPayloadHash,
     };
   } catch (e) {
     console.log('Notification encryption failed: ' + e);
@@ -217,6 +224,7 @@
     +deviceToken: string,
     +notification: apn.Notification,
     +payloadSizeExceeded: boolean,
+    +encryptedPayloadHash?: string,
   }>,
 > {
   const notificationPromises = devices.map(
diff --git a/keyserver/src/push/send.js b/keyserver/src/push/send.js
--- a/keyserver/src/push/send.js
+++ b/keyserver/src/push/send.js
@@ -794,9 +794,10 @@
 
   if (devicesWithExcessiveSize.length === 0) {
     return notifsWithMessageInfos.map(
-      ({ notification: notif, deviceToken }) => ({
+      ({ notification: notif, deviceToken, encryptedPayloadHash }) => ({
         notification: notif,
         deviceToken,
+        encryptedPayloadHash,
       }),
     );
   }
@@ -809,15 +810,17 @@
 
   const targetedNotifsWithMessageInfos = notifsWithMessageInfos
     .filter(({ payloadSizeExceeded }) => !payloadSizeExceeded)
-    .map(({ notification: notif, deviceToken }) => ({
+    .map(({ notification: notif, deviceToken, encryptedPayloadHash }) => ({
       notification: notif,
       deviceToken,
+      encryptedPayloadHash,
     }));
 
   const targetedNotifsWithoutMessageInfos = notifsWithoutMessageInfos.map(
-    ({ notification: notif, deviceToken }) => ({
+    ({ notification: notif, deviceToken, encryptedPayloadHash }) => ({
       notification: notif,
       deviceToken,
+      encryptedPayloadHash,
     }),
   );
 
@@ -1053,6 +1056,7 @@
   codeVersion: number,
   stateVersion: number,
   errors?: $ReadOnlyArray<ResponseFailure>,
+  encryptedPayloadHashes?: $ReadOnlyArray<string>,
 };
 type APNsResult = {
   info: NotificationInfo,
@@ -1090,6 +1094,17 @@
   if (response.errors) {
     delivery.errors = response.errors;
   }
+
+  const encryptedPayloadHashes = [];
+  for (const targetedNotification of targetedNotifications) {
+    if (targetedNotification.encryptedPayloadHash) {
+      encryptedPayloadHashes.push(targetedNotification.encryptedPayloadHash);
+    }
+  }
+  if (encryptedPayloadHashes.length !== 0) {
+    delivery.encryptedPayloadHashes = encryptedPayloadHashes;
+  }
+
   const result: APNsResult = {
     info: notificationInfo,
     delivery,
diff --git a/keyserver/src/push/types.js b/keyserver/src/push/types.js
--- a/keyserver/src/push/types.js
+++ b/keyserver/src/push/types.js
@@ -5,6 +5,7 @@
 export type TargetedAPNsNotification = {
   +notification: apn.Notification,
   +deviceToken: string,
+  +encryptedPayloadHash?: string,
 };
 
 type AndroidNotificationPayloadBase = {