diff --git a/keyserver/src/creators/account-creator.js b/keyserver/src/creators/account-creator.js
--- a/keyserver/src/creators/account-creator.js
+++ b/keyserver/src/creators/account-creator.js
@@ -32,6 +32,7 @@
 
 import createIDs from './id-creator.js';
 import createMessages from './message-creator.js';
+import { createOlmSession } from './olm-session-creator.js';
 import {
   createThread,
   createPrivateThread,
@@ -83,7 +84,11 @@
     WHERE LCASE(username) = LCASE(${request.username})
   `;
   const promises = [dbQuery(usernameQuery)];
-  const { calendarQuery, signedIdentityKeysBlob } = request;
+  const {
+    calendarQuery,
+    signedIdentityKeysBlob,
+    initialNotificationsEncryptedMessage,
+  } = request;
   if (calendarQuery) {
     promises.push(verifyCalendarQueryThreadIDs(calendarQuery));
   }
@@ -130,6 +135,16 @@
     await setNewSession(viewer, calendarQuery, 0);
   }
 
+  const olmSessionPromise = (async () => {
+    if (userViewerData.cookieID && initialNotificationsEncryptedMessage) {
+      await createOlmSession(
+        initialNotificationsEncryptedMessage,
+        'notifications',
+        userViewerData.cookieID,
+      );
+    }
+  })();
+
   await Promise.all([
     updateThread(
       createScriptViewer(ashoat.id),
@@ -140,6 +155,7 @@
       { forceAddMembers: true, silenceMessages: true, ignorePermissions: true },
     ),
     viewerAcknowledgmentUpdater(viewer, policyTypes.tosAndPrivacyPolicy),
+    olmSessionPromise,
   ]);
 
   const [privateThreadResult, ashoatThreadResult] = await Promise.all([
diff --git a/keyserver/src/responders/user-responders.js b/keyserver/src/responders/user-responders.js
--- a/keyserver/src/responders/user-responders.js
+++ b/keyserver/src/responders/user-responders.js
@@ -280,6 +280,7 @@
   // old clients, but we no longer do anything with it.
   primaryIdentityPublicKey: t.maybe(tRegex(primaryIdentityPublicKeyRegex)),
   signedIdentityKeysBlob: t.maybe(signedIdentityKeysBlobValidator),
+  initialNotificationsEncryptedMessage: t.maybe(t.String),
 });
 
 export const registerResponseValidator: TInterface<RegisterResponse> =
diff --git a/lib/types/account-types.js b/lib/types/account-types.js
--- a/lib/types/account-types.js
+++ b/lib/types/account-types.js
@@ -58,6 +58,7 @@
   +platformDetails: PlatformDetails,
   +primaryIdentityPublicKey?: empty,
   +signedIdentityKeysBlob?: SignedIdentityKeysBlob,
+  +initialNotificationsEncryptedMessage?: string,
 };
 
 export type RegisterResponse = {
diff --git a/native/account/register-panel.react.js b/native/account/register-panel.react.js
--- a/native/account/register-panel.react.js
+++ b/native/account/register-panel.react.js
@@ -37,6 +37,7 @@
 import { useSelector } from '../redux/redux-utils.js';
 import { nativeLogInExtraInfoSelector } from '../selectors/account-selectors.js';
 import type { KeyPressEvent } from '../types/react-native.js';
+import { useInitialNotificationsEncryptedMessage } from '../utils/crypto-utils.js';
 import { type StateContainer } from '../utils/state-container.js';
 
 export type RegisterState = {
@@ -55,6 +56,7 @@
   +logInExtraInfo: () => Promise<LogInExtraInfo>,
   +dispatchActionPromise: DispatchActionPromise,
   +register: (registerInfo: RegisterInfo) => Promise<RegisterResult>,
+  +getInitialNotificationsEncryptedMessage: () => Promise<string>,
 };
 type State = {
   +confirmPasswordFocused: boolean,
@@ -289,9 +291,14 @@
     } else {
       Keyboard.dismiss();
       const extraInfo = await this.props.logInExtraInfo();
+      const initialNotificationsEncryptedMessage =
+        await this.props.getInitialNotificationsEncryptedMessage();
       this.props.dispatchActionPromise(
         registerActionTypes,
-        this.registerAction(extraInfo),
+        this.registerAction({
+          ...extraInfo,
+          initialNotificationsEncryptedMessage,
+        }),
         undefined,
         ({ calendarQuery: extraInfo.calendarQuery }: LogInStartingPayload),
       );
@@ -457,6 +464,8 @@
 
     const dispatchActionPromise = useDispatchActionPromise();
     const callRegister = useServerCall(register);
+    const getInitialNotificationsEncryptedMessage =
+      useInitialNotificationsEncryptedMessage();
 
     return (
       <RegisterPanel
@@ -465,6 +474,9 @@
         logInExtraInfo={logInExtraInfo}
         dispatchActionPromise={dispatchActionPromise}
         register={callRegister}
+        getInitialNotificationsEncryptedMessage={
+          getInitialNotificationsEncryptedMessage
+        }
       />
     );
   });