Make non-fwded messages sent to yourself outgoing

telethon/events/newmessage.py

@@ -91,6 +91,14 @@ class NewMessage(EventBuilder):
             return
 
         event._entities = update._entities
+
+        # Make messages sent to ourselves outgoing unless they're forwarded.
+        # This makes it consistent with official client's appearance.
+        ori = event.message
+        if isinstance(ori.to_id, types.PeerUser):
+            if ori.from_id == ori.to_id.user_id and not ori.fwd_from:
+                event.message.out = True
+
         return self._message_filter_event(event)
 
     def _message_filter_event(self, event):

telethon/tl/custom/message.py

@@ -401,6 +401,12 @@ class Message:
         """
         Whether the message is outgoing (i.e. you sent it from
         another session) or incoming (i.e. someone else sent it).
+
+        Note that messages in your own chat are always incoming,
+        but this property will be ``True`` if you send a message
+        to your own chat. Messages you forward to your chat are
+        *not* considered outgoing, just like official clients
+        display them.
         """
         return self.original_message.out