diff --git a/deploy-chatmail/src/deploy_chatmail/dovecot/dovecot.conf.j2 b/deploy-chatmail/src/deploy_chatmail/dovecot/dovecot.conf.j2
index 0e2a7ca1..5834e717 100644
--- a/deploy-chatmail/src/deploy_chatmail/dovecot/dovecot.conf.j2
+++ b/deploy-chatmail/src/deploy_chatmail/dovecot/dovecot.conf.j2
@@ -79,7 +79,7 @@ plugin {
   quota_rule = *:storage=100M
   quota_max_mail_size=30M
   quota_grace = 0
-  quota_over_flag_value = TRUE
+  # quota_over_flag_value = TRUE
 }
 
 
diff --git a/deploy-chatmail/src/deploy_chatmail/postfix/main.cf.j2 b/deploy-chatmail/src/deploy_chatmail/postfix/main.cf.j2
index 7508e460..303aed13 100644
--- a/deploy-chatmail/src/deploy_chatmail/postfix/main.cf.j2
+++ b/deploy-chatmail/src/deploy_chatmail/postfix/main.cf.j2
@@ -37,6 +37,8 @@ mydestination =
 relayhost = 
 mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
 mailbox_size_limit = 0
+# maximum 30MB sized messages
+message_size_limit = 31457280
 recipient_delimiter = +
 inet_interfaces = all
 inet_protocols = all
diff --git a/deploy-chatmail/src/deploy_chatmail/postfix/master.cf b/deploy-chatmail/src/deploy_chatmail/postfix/master.cf
index 310542a3..e071acf0 100644
--- a/deploy-chatmail/src/deploy_chatmail/postfix/master.cf
+++ b/deploy-chatmail/src/deploy_chatmail/postfix/master.cf
@@ -9,7 +9,7 @@
 # service type  private unpriv  chroot  wakeup  maxproc command + args
 #               (yes)   (yes)   (no)    (never) (100)
 # ==========================================================================
-smtp      inet  n       -       y       -       -       smtpd
+smtp      inet  n       -       y       -       -       smtpd -v 
 #smtp      inet  n       -       y       -       1       postscreen
 #smtpd     pass  -       -       y       -       -       smtpd
 #dnsblog   unix  -       -       y       -       0       dnsblog
diff --git a/online-tests/conftest.py b/online-tests/conftest.py
index ef9688e1..86d99d29 100644
--- a/online-tests/conftest.py
+++ b/online-tests/conftest.py
@@ -1,5 +1,6 @@
 import os
 import io
+import random
 import imaplib
 import smtplib
 import itertools
@@ -50,13 +51,15 @@ class SmtpConn:
 
 @pytest.fixture
 def gencreds(maildomain):
-    prefix = str(time.time())
     count = itertools.count()
 
     def gen():
         while 1:
             num = next(count)
-            yield f"user{prefix}_{num}@{maildomain}", f"password{prefix}_{num}"
+            alphanumeric = "abcdefghijklmnopqrstuvwxyz1234567890"
+            user = "".join(random.choices(alphanumeric, k=10))
+            password = "".join(random.choices(alphanumeric, k=10))
+            yield f"{user}@{maildomain}", f"{password}"
 
     return lambda: next(gen())
 
@@ -99,7 +102,7 @@ def cmfactory(request, maildomain, gencreds, tmpdir, data):
     am = ACFactory(request=request, tmpdir=tmpdir, testprocess=testproc, data=data)
     yield am
     if hasattr(request.node, "rep_call") and request.node.rep_call.failed:
-        if testprocess.pytestconfig.getoption("--extra-info"):
+        if testproc.pytestconfig.getoption("--extra-info"):
             logfile = io.StringIO()
             am.dump_imap_summary(logfile=logfile)
             print(logfile.getvalue())
diff --git a/online-tests/test_1_deltachat.py b/online-tests/test_1_deltachat.py
index 1439898b..86e0d5d7 100644
--- a/online-tests/test_1_deltachat.py
+++ b/online-tests/test_1_deltachat.py
@@ -1,3 +1,7 @@
+import random
+import pytest
+
+
 class TestMailSending:
     def test_one_on_one(self, cmfactory, lp):
         ac1, ac2 = cmfactory.get_online_accounts(2)
@@ -9,3 +13,41 @@ 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)
+
+        quota = 1024 * 1024 * 100
+        attachsize = 1 * 1024 * 1024
+        num_to_send = quota // attachsize + 2
+        lp.sec(f"ac1: send {num_to_send} large files to ac2")
+        lp.indent(f"per-user quota is assumed to be: {quota/(1024*1024)}MB")
+        alphanumeric = "abcdefghijklmnopqrstuvwxyz1234567890"
+        msgs = []
+        for i in range(num_to_send):
+            attachment = tmpdir / f"attachment{i}"
+            data = "".join(random.choice(alphanumeric) for i in range(1024))
+            with open(attachment, "w+") as f:
+                for j in range(attachsize // len(data)):
+                    f.write(data)
+
+            msg = chat.send_file(str(attachment))
+            msgs.append(msg)
+            lp.indent(f"Sent out msg {i}, size {attachsize/(1024*1024)}MB")
+
+        lp.sec("ac2: check that at least one message failed due to quota")
+        bytes_sent = 0
+        for i, msg in enumerate(msgs):
+            # wait for the message to be received
+            msg_received = ac2.wait_next_incoming_message()
+            if msg.is_out_failed():
+                assert bytes_sent + 10 * 1024*1024 > quota, "quota kicked in too early"
+                lp.indent("good, message sending failed because quota was exceeded")
+                lp.indent(chat.get_messages()[i].get_message_info())
+                return
+            assert msg.is_out_delivered(), msg.get_message_info()
+            bytes_sent += attachsize
+            mb = bytes_sent // (1024*1024)
+            lp.indent(f"message {i} success, bytes transmitted so far {mb}MB")
+        pytest.fail("sending succeeded although messages should exceed quota")