tried to write a test to test exceeded quota, but not sure delta even gets a proper error on recipient's full mailbox

online-tests/test_1_deltachat.py

@@ -1,3 +1,8 @@
+import os.path
+import random
+import time
+
+
 class TestMailSending:
     def test_one_on_one(self, cmfactory, lp):
         ac1, ac2 = cmfactory.get_online_accounts(2)
@@ -9,3 +14,32 @@ class TestMailSending:
         lp.sec("wait for ac2 to receive message")
         msg2 = ac2._evtracker.wait_next_incoming_message()
         assert msg2.text == "message0"
+
+    def test_exceed_quota(self, cmfactory, lp, tmpdir):
+        ac1, ac2 = cmfactory.get_online_accounts(2)
+        chat = cmfactory.get_accepted_chat(ac1, ac2)
+
+        ac2.set_config("download_limit", 1024 * 2)  # set download_limit to 2 KB avoid downloading all those 5MB files
+
+        lp.sec("ac1: send 25 5 MB files to ac2")
+        alphanumeric = "abcdefghijklmnopqrstuvwxyz1234567890"
+        for i in range(25):
+            attachment = tmpdir / f"attachment{i}"
+            with open(attachment, "w+") as f:
+                for j in range(1024 * 1024 * 5):
+                    f.write(random.choice(alphanumeric))
+
+            print("Sent out msg", str(i))
+            chat.send_file(str(attachment))
+
+        ac2.wait_next_incoming_message()
+        lp.sec("ac2: check that at least one message failed")
+        failed = False
+        for i in range(25):
+            if chat.get_messages()[i].is_out_failed():
+                failed = True
+                print(chat.get_messages()[i].get_message_info())
+        try:
+            assert failed
+        except:
+            import pdb; pdb.set_trace()