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
@@ -40,7 +40,13 @@
 import { fetchUserInfos } from '../fetchers/user-fetchers';
 import type { Viewer } from '../session/viewer';
 import { getAPNsNotificationTopic } from './providers';
-import { apnPush, fcmPush, getUnreadCounts } from './utils';
+import {
+  apnPush,
+  fcmPush,
+  getUnreadCounts,
+  apnMaxMessagePayloadByteSize,
+  fcmMaxMessagePayloadByteSize,
+} from './utils';
 
 type Device = {
   +deviceType: DeviceType,
@@ -167,6 +173,7 @@
             unreadCounts[userID],
             codeVersion,
           );
+          validateIOSNotificationByteSize(notification);
           deliveryPromises.push(
             sendIOSNotification(notification, [...deviceTokens], {
               ...notificationInfo,
@@ -193,6 +200,7 @@
             dbID,
             codeVersion,
           );
+          validateAndroidNotificationByteSize(notification);
           deliveryPromises.push(
             sendAndroidNotification(notification, [...deviceTokens], {
               ...notificationInfo,
@@ -502,6 +510,15 @@
   return notification;
 }
 
+function validateIOSNotificationByteSize(notification: apn.Notification) {
+  if (
+    Buffer.byteLength(JSON.stringify(notification)) >
+    apnMaxMessagePayloadByteSize
+  ) {
+    delete notification.payload.messageInfos;
+  }
+}
+
 function prepareAndroidNotification(
   allMessageInfos: MessageInfo[],
   newRawMessageInfos: RawMessageInfo[],
@@ -565,6 +582,20 @@
   };
 }
 
+function validateAndroidNotificationByteSize(notification: Object) {
+  const notificationByteSizeExceeded =
+    Buffer.byteLength(JSON.stringify(notification)) >
+    fcmMaxMessagePayloadByteSize;
+  if (
+    notificationByteSizeExceeded &&
+    'custom_notification' in notification.data
+  ) {
+    delete notification.data.custom_notification.messageInfos;
+  } else if (notificationByteSizeExceeded) {
+    delete notification.data.messageInfos;
+  }
+}
+
 type NotificationInfo =
   | {
       +source: 'new_message',