diff --git a/js/background.js b/js/background.js
index 71db33e0752..a6c8a01c9a1 100644
--- a/js/background.js
+++ b/js/background.js
@@ -2071,6 +2071,9 @@
     return confirm();
   }
 
+  // Note: We do very little in this function, since everything in handleDataMessage is
+  //   inside a conversation-specific queue(). Any code here might run before an earlier
+  //   message is processed in handleDataMessage().
   async function onMessageReceived(event) {
     const { data, confirm } = event;
 
@@ -2090,27 +2093,6 @@
 
     const message = await initIncomingMessage(data);
 
-    const ourNumber = textsecure.storage.user.getNumber();
-    const isGroupUpdate =
-      data.message.group &&
-      data.message.group.type !== textsecure.protobuf.GroupContext.Type.DELIVER;
-    const conversation = ConversationController.get(messageDescriptor.id);
-
-    // We drop messages for groups we already know about, which we're not a part of,
-    //   except for group updates
-    if (
-      conversation &&
-      !conversation.isPrivate() &&
-      !conversation.hasMember(ourNumber) &&
-      !isGroupUpdate
-    ) {
-      window.log.warn(
-        `Received message destined for group ${conversation.idForLogging()}, which we're not a part of. Dropping.`
-      );
-      confirm();
-      return;
-    }
-
     await ConversationController.getOrCreateAndWait(
       messageDescriptor.id,
       messageDescriptor.type
@@ -2134,12 +2116,9 @@
     }
 
     // Don't wait for handleDataMessage, as it has its own per-conversation queueing
-    message.handleDataMessage(data.message, event.confirm, {
-      initialLoadComplete,
-    });
+    message.handleDataMessage(data.message, event.confirm);
   }
 
-  // Sent:
   async function handleMessageSentProfileUpdate({
     data,
     confirm,
@@ -2196,6 +2175,9 @@
     });
   }
 
+  // Note: We do very little in this function, since everything in handleDataMessage is
+  //   inside a conversation-specific queue(). Any code here might run before an earlier
+  //   message is processed in handleDataMessage().
   async function onSentMessage(event) {
     const { data, confirm } = event;
 
@@ -2214,44 +2196,8 @@
     }
 
     const message = await createSentMessage(data);
-    const existing = await getExistingMessage(message.attributes);
-    const isUpdate = Boolean(data.isRecipientUpdate);
 
-    if (isUpdate && existing) {
-      event.confirm();
-
-      let sentTo = [];
-      let unidentifiedDeliveries = [];
-      if (Array.isArray(data.unidentifiedStatus)) {
-        sentTo = data.unidentifiedStatus.map(item => item.destination);
-
-        const unidentified = _.filter(data.unidentifiedStatus, item =>
-          Boolean(item.unidentified)
-        );
-        unidentifiedDeliveries = unidentified.map(item => item.destination);
-      }
-
-      existing.set({
-        sent_to: _.union(existing.get('sent_to'), sentTo),
-        unidentifiedDeliveries: _.union(
-          existing.get('unidentifiedDeliveries'),
-          unidentifiedDeliveries
-        ),
-      });
-      await window.Signal.Data.saveMessage(existing.attributes, {
-        Message: Whisper.Message,
-      });
-    } else if (isUpdate) {
-      window.log.warn(
-        `onSentMessage: Received update transcript, but no existing entry for message ${message.idForLogging()}. Dropping.`
-      );
-      event.confirm();
-    } else if (existing) {
-      window.log.warn(
-        `onSentMessage: Received duplicate transcript for message ${message.idForLogging()}, but it was not an update transcript. Dropping.`
-      );
-      event.confirm();
-    } else if (data.message.reaction) {
+    if (data.message.reaction) {
       const { reaction } = data.message;
       const ourNumber = textsecure.storage.user.getNumber();
       const reactionModel = Whisper.Reactions.add({
@@ -2266,35 +2212,20 @@
       });
       // Note: We do not wait for completion here
       Whisper.Reactions.onReaction(reactionModel);
+
       event.confirm();
-    } else {
-      await ConversationController.getOrCreateAndWait(
-        messageDescriptor.id,
-        messageDescriptor.type
-      );
-
-      // Don't wait for handleDataMessage, as it has its own per-conversation queueing
-      message.handleDataMessage(data.message, event.confirm, {
-        initialLoadComplete,
-      });
+      return;
     }
-  }
 
-  async function getExistingMessage(data) {
-    try {
-      const result = await window.Signal.Data.getMessageBySender(data, {
-        Message: Whisper.Message,
-      });
+    await ConversationController.getOrCreateAndWait(
+      messageDescriptor.id,
+      messageDescriptor.type
+    );
 
-      if (result) {
-        return MessageController.register(result.id, result);
-      }
-
-      return null;
-    } catch (error) {
-      window.log.error('getExistingMessage error:', Errors.toLogFormat(error));
-      return false;
-    }
+    // Don't wait for handleDataMessage, as it has its own per-conversation queueing
+    message.handleDataMessage(data.message, event.confirm, {
+      data,
+    });
   }
 
   async function initIncomingMessage(data) {
@@ -2413,7 +2344,12 @@
 
       // This matches the queueing behavior used in Message.handleDataMessage
       conversation.queueJob(async () => {
-        const existingMessage = await getExistingMessage(message.attributes);
+        const existingMessage = await window.Signal.Data.getMessageBySender(
+          message.attributes,
+          {
+            Message: Whisper.Message,
+          }
+        );
         if (existingMessage) {
           ev.confirm();
           window.log.warn(
diff --git a/js/models/messages.js b/js/models/messages.js
index bb522327463..4b3500922ce 100644
--- a/js/models/messages.js
+++ b/js/models/messages.js
@@ -1406,11 +1406,7 @@
 
           // This is used by sendSyncMessage, then set to null
           if (result.dataMessage) {
-            // When we're not sending recipient updates, we won't save the dataMessage
-            //   unless it's the first time we attempt to send the message.
-            if (!this.get('synced') || window.SEND_RECIPIENT_UPDATES) {
-              this.set({ dataMessage: result.dataMessage });
-            }
+            this.set({ dataMessage: result.dataMessage });
           }
 
           const sentTo = this.get('sent_to') || [];
@@ -1547,11 +1543,6 @@
         }
         const isUpdate = Boolean(this.get('synced'));
 
-        // Until isRecipientUpdate sync messages are widely supported, will not send them
-        if (isUpdate && !window.SEND_RECIPIENT_UPDATES) {
-          return Promise.resolve();
-        }
-
         return wrap(
           textsecure.messaging.sendSyncMessage(
             dataMessage,
@@ -1872,7 +1863,9 @@
       return message;
     },
 
-    handleDataMessage(initialMessage, confirm) {
+    handleDataMessage(initialMessage, confirm, options = {}) {
+      const { data } = options;
+
       // This function is called from the background script in a few scenarios:
       //   1. on an incoming message
       //   2. on a sent message sync'd from another device
@@ -1897,11 +1890,85 @@
         const existingMessage = await getMessageBySender(this.attributes, {
           Message: Whisper.Message,
         });
-        if (existingMessage) {
+        const isUpdate = Boolean(data && data.isRecipientUpdate);
+
+        if (existingMessage && type === 'incoming') {
           window.log.warn('Received duplicate message', this.idForLogging());
           confirm();
           return;
         }
+        if (type === 'outgoing') {
+          if (isUpdate && existingMessage) {
+            window.log.info(
+              `handleDataMessage: Updating message ${message.idForLogging()} with received transcript`
+            );
+
+            let sentTo = [];
+            let unidentifiedDeliveries = [];
+            if (Array.isArray(data.unidentifiedStatus)) {
+              sentTo = data.unidentifiedStatus.map(item => item.destination);
+
+              const unidentified = _.filter(data.unidentifiedStatus, item =>
+                Boolean(item.unidentified)
+              );
+              unidentifiedDeliveries = unidentified.map(
+                item => item.destination
+              );
+            }
+
+            const toUpdate = MessageController.register(
+              existingMessage.id,
+              existingMessage
+            );
+            toUpdate.set({
+              sent_to: _.union(toUpdate.get('sent_to'), sentTo),
+              unidentifiedDeliveries: _.union(
+                toUpdate.get('unidentifiedDeliveries'),
+                unidentifiedDeliveries
+              ),
+            });
+            await window.Signal.Data.saveMessage(toUpdate.attributes, {
+              Message: Whisper.Message,
+            });
+
+            confirm();
+            return;
+          } else if (isUpdate) {
+            window.log.warn(
+              `handleDataMessage: Received update transcript, but no existing entry for message ${message.idForLogging()}. Dropping.`
+            );
+
+            confirm();
+            return;
+          } else if (existingMessage) {
+            window.log.warn(
+              `handleDataMessage: Received duplicate transcript for message ${message.idForLogging()}, but it was not an update transcript. Dropping.`
+            );
+
+            confirm();
+            return;
+          }
+        }
+
+        // We drop incoming messages for groups we already know about, which we're not a
+        //   part of, except for group updates.
+        const ourNumber = textsecure.storage.user.getNumber();
+        const isGroupUpdate =
+          initialMessage.group &&
+          initialMessage.group.type !==
+            textsecure.protobuf.GroupContext.Type.DELIVER;
+        if (
+          type === 'incoming' &&
+          !conversation.isPrivate() &&
+          !conversation.hasMember(ourNumber) &&
+          !isGroupUpdate
+        ) {
+          window.log.warn(
+            `Received message destined for group ${conversation.idForLogging()}, which we're not a part of. Dropping.`
+          );
+          confirm();
+          return;
+        }
 
         // Send delivery receipts, but only for incoming sealed sender messages
         if (
diff --git a/libtextsecure/message_receiver.js b/libtextsecure/message_receiver.js
index be30ae91edf..5a785d8bc21 100644
--- a/libtextsecure/message_receiver.js
+++ b/libtextsecure/message_receiver.js
@@ -1239,19 +1239,17 @@ MessageReceiver.prototype.extend({
     // Note that messages may (generally) only perform one action and we ignore remaining
     //   fields after the first action.
 
-    if (window.TIMESTAMP_VALIDATION) {
-      if (!envelope.timestamp || !decrypted.timestamp) {
-        throw new Error('Missing timestamp on dataMessage or envelope');
-      }
+    if (!envelope.timestamp || !decrypted.timestamp) {
+      throw new Error('Missing timestamp on dataMessage or envelope');
+    }
 
-      const envelopeTimestamp = envelope.timestamp.toNumber();
-      const decryptedTimestamp = decrypted.timestamp.toNumber();
+    const envelopeTimestamp = envelope.timestamp.toNumber();
+    const decryptedTimestamp = decrypted.timestamp.toNumber();
 
-      if (envelopeTimestamp !== decryptedTimestamp) {
-        throw new Error(
-          `Timestamp ${decrypted.timestamp} in DataMessage did not match envelope timestamp ${envelope.timestamp}`
-        );
-      }
+    if (envelopeTimestamp !== decryptedTimestamp) {
+      throw new Error(
+        `Timestamp ${decrypted.timestamp} in DataMessage did not match envelope timestamp ${envelope.timestamp}`
+      );
     }
 
     if (decrypted.flags == null) {
diff --git a/libtextsecure/sendmessage.js b/libtextsecure/sendmessage.js
index 019cfd854ae..8c824f4dc31 100644
--- a/libtextsecure/sendmessage.js
+++ b/libtextsecure/sendmessage.js
@@ -188,11 +188,7 @@ MessageSender.prototype = {
     );
   },
 
-  getPaddedAttachment(data, shouldPad) {
-    if (!window.PAD_ALL_ATTACHMENTS && !shouldPad) {
-      return data;
-    }
-
+  getPaddedAttachment(data) {
     const size = data.byteLength;
     const paddedSize = this._getAttachmentSizeBucket(size);
     const padding = window.Signal.Crypto.getZeroes(paddedSize - size);
@@ -200,7 +196,7 @@ MessageSender.prototype = {
     return window.Signal.Crypto.concatenateBytes(data, padding);
   },
 
-  async makeAttachmentPointer(attachment, shouldPad = false) {
+  async makeAttachmentPointer(attachment) {
     if (typeof attachment !== 'object' || attachment == null) {
       return Promise.resolve(undefined);
     }
@@ -217,7 +213,7 @@ MessageSender.prototype = {
       );
     }
 
-    const padded = this.getPaddedAttachment(data, shouldPad);
+    const padded = this.getPaddedAttachment(data);
     const key = libsignal.crypto.getRandomBytes(64);
     const iv = libsignal.crypto.getRandomBytes(16);
 
@@ -308,14 +304,10 @@ MessageSender.prototype = {
         return;
       }
 
-      const shouldPad = true;
       // eslint-disable-next-line no-param-reassign
       message.sticker = {
         ...sticker,
-        attachmentPointer: await this.makeAttachmentPointer(
-          sticker.data,
-          shouldPad
-        ),
+        attachmentPointer: await this.makeAttachmentPointer(sticker.data),
       };
     } catch (error) {
       if (error instanceof Error && error.name === 'HTTPError') {
diff --git a/preload.js b/preload.js
index 6f3c5b083af..a877a2c3675 100644
--- a/preload.js
+++ b/preload.js
@@ -11,11 +11,6 @@ const { remote } = electron;
 const { app } = remote;
 const { systemPreferences } = remote.require('electron');
 
-// Waiting for clients to implement changes on receive side
-window.TIMESTAMP_VALIDATION = false;
-window.PAD_ALL_ATTACHMENTS = false;
-window.SEND_RECIPIENT_UPDATES = false;
-
 window.PROTO_ROOT = 'protos';
 const config = require('url').parse(window.location.toString(), true).query;