diff --git a/app/src/main/java/eu/faircode/email/DaoMessage.java b/app/src/main/java/eu/faircode/email/DaoMessage.java
index a10d3d86f7..b9851e21d3 100644
--- a/app/src/main/java/eu/faircode/email/DaoMessage.java
+++ b/app/src/main/java/eu/faircode/email/DaoMessage.java
@@ -170,10 +170,9 @@ public interface DaoMessage {
     @Query("SELECT message.* FROM message" +
             " JOIN folder ON folder.id = message.folder" +
             " WHERE message.account = :account" +
-            " AND (message.msgid = :msgid" +
-            " OR message.msgid = :reference)" +
+            " AND message.msgid = :msgid" +
             " AND ui_found = :found")
-    List<EntityMessage> getMessageByMsgId(long account, String msgid, String reference, boolean found);
+    List<EntityMessage> getMessageByMsgId(long account, String msgid, boolean found);
 
     @Query("SELECT * FROM message" +
             " WHERE folder = :folder" +
diff --git a/app/src/main/java/eu/faircode/email/MessageHelper.java b/app/src/main/java/eu/faircode/email/MessageHelper.java
index bc2e43bf21..5ee6ee00c3 100644
--- a/app/src/main/java/eu/faircode/email/MessageHelper.java
+++ b/app/src/main/java/eu/faircode/email/MessageHelper.java
@@ -187,6 +187,7 @@ public class MessageHelper {
             imessage.addHeader("References", (replying.references == null ? "" : replying.references + " ") + replying.msgid);
         }
 
+        imessage.addHeader("X-FairEmail-ID", message.msgid);
         imessage.addHeader("X-FairEmail-Thread", message.thread);
 
         imessage.setFlag(Flags.Flag.SEEN, message.seen);
@@ -368,6 +369,11 @@ public class MessageHelper {
     }
 
     String getMessageID() throws MessagingException {
+        // Outlook outbox -> sent
+        String[] xID = imessage.getHeader("X-FairEmail-ID");
+        if (xID != null && xID.length > 0)
+            return xID[0];
+
         return imessage.getHeader("Message-ID", null);
     }
 
@@ -385,6 +391,7 @@ public class MessageHelper {
     }
 
     String getThreadId(long uid) throws MessagingException {
+        // Some providers break references when moving messages
         String[] xThread = imessage.getHeader("X-FairEmail-Thread");
         if (xThread != null && xThread.length > 0)
             return xThread[0];
@@ -392,6 +399,7 @@ public class MessageHelper {
         for (String ref : getReferences())
             if (!TextUtils.isEmpty(ref))
                 return ref;
+
         String msgid = getMessageID();
         return (TextUtils.isEmpty(msgid) ? Long.toString(uid) : msgid);
     }
diff --git a/app/src/main/java/eu/faircode/email/ServiceSynchronize.java b/app/src/main/java/eu/faircode/email/ServiceSynchronize.java
index 67f23a641a..7286e0061f 100644
--- a/app/src/main/java/eu/faircode/email/ServiceSynchronize.java
+++ b/app/src/main/java/eu/faircode/email/ServiceSynchronize.java
@@ -2021,9 +2021,8 @@ public class ServiceSynchronize extends LifecycleService {
             // Will fetch headers within database transaction
             String msgid = helper.getMessageID();
             String[] refs = helper.getReferences();
-            String reference = (refs.length == 1 && refs[0].indexOf(BuildConfig.APPLICATION_ID) > 0 ? refs[0] : msgid);
-            Log.i(Helper.TAG, "Searching for " + msgid + " / " + reference);
-            for (EntityMessage dup : db.message().getMessageByMsgId(folder.account, msgid, reference, found)) {
+            Log.i(Helper.TAG, "Searching for " + msgid);
+            for (EntityMessage dup : db.message().getMessageByMsgId(folder.account, msgid, found)) {
                 EntityFolder dfolder = db.folder().getFolder(dup.folder);
                 boolean outbox = EntityFolder.OUTBOX.equals(dfolder.type);
                 Log.i(Helper.TAG, folder.name + " found as id=" + dup.id + "/" + dup.uid +