feat: Don't mark messages as seen on IMAP if bcc_self=0 or bot=1

bcc_self=0 means that the user disabled it or it's a chatmail setup with the only device and w/o
backups. If a backup is made someday, old messages not marked as IMAP-seen aren't a problem and new
ones are marked as IMAP-seen.

For bots, particularly multi-device ones (which are a rare case), probably no sane logic can be
built on the "seen" message status. Moreover, if the user has additionally a bot that reads incoming
messages, it doesn't mean that the user doesn't want to read them too.

deltachat-rpc-client/tests/test_folders.py

@@ -11,6 +11,7 @@ def test_moved_markseen(acfactory, direct_imap, log):
 
     addr, password = acfactory.get_credentials()
     ac2 = acfactory.get_unconfigured_account()
+    ac2.set_config("bcc_self", "1")
     ac2.add_or_update_transport({"addr": addr, "password": password})
     ac2.bring_online()
 
@@ -60,8 +61,8 @@ def test_markseen_message_and_mdn(acfactory, direct_imap):
     for ac in ac1, ac2:
         ac.set_config("delete_server_after", "0")
 
-    # Do not send BCC to self, we only want to test MDN on ac1.
-    ac1.set_config("bcc_self", "0")
+    # For ac1, we only want to test MDN.
+    ac2.set_config("bcc_self", "1")
 
     acfactory.get_accepted_chat(ac1, ac2).send_text("hi")
     msg = ac2.wait_for_incoming_msg()

deltachat-rpc-client/tests/test_multidevice.py

@@ -79,7 +79,6 @@ def test_one_account_send_bcc_setting(acfactory, log, direct_imap):
 
     # now make sure we are sending message to ourselves too
     assert self_addr in ev.msg
-    assert self_addr in ev.msg
 
     # BCC-self messages are marked as seen by the sender device.
     while True: