diff --git a/scripts/test.sh b/scripts/test.sh
index 7df894ac..6889c407 100755
--- a/scripts/test.sh
+++ b/scripts/test.sh
@@ -1,4 +1,4 @@
 #!/bin/bash
 venv/bin/tox -c chatmaild
 venv/bin/tox -c deploy-chatmail
-venv/bin/pytest tests/online -vrx --durations=5 $@
+venv/bin/pytest tests/online -rs -vrx --durations=5 $@
diff --git a/tests/chatmaild/test_dictproxy.py b/tests/chatmaild/test_dictproxy.py
index 0eec33cb..409eeb7d 100644
--- a/tests/chatmaild/test_dictproxy.py
+++ b/tests/chatmaild/test_dictproxy.py
@@ -1,21 +1,15 @@
-import os
 import json
 
 import pytest
+import threading
+import queue
+import traceback
 
 import chatmaild.dictproxy
 from chatmaild.dictproxy import get_user_data, lookup_passdb, handle_dovecot_request
 from chatmaild.database import Database, DBError
 
 
-@pytest.fixture()
-def db(tmpdir):
-    db_path = tmpdir / "passdb.sqlite"
-    print("database path:", db_path)
-    return Database(db_path)
-
-
-
 def test_basic(db):
     lookup_passdb(db, "link2xt@c1.testrun.org", "Pieg9aeToe3eghuthe5u")
     data = get_user_data(db, "link2xt@c1.testrun.org")
@@ -53,8 +47,10 @@ def test_too_high_db_version(db):
 
 
 def test_handle_dovecot_request(db):
-    msg = ('Lshared/passdb/laksjdlaksjdlaksjdlk12j3l1k2j3123/'
-           'some42@c3.testrun.org\tsome42@c3.testrun.org')
+    msg = (
+        "Lshared/passdb/laksjdlaksjdlaksjdlk12j3l1k2j3123/"
+        "some42@c3.testrun.org\tsome42@c3.testrun.org"
+    )
     res = handle_dovecot_request(msg, db, "c3.testrun.org")
     assert res
     assert res[0] == "O" and res.endswith("\n")
@@ -62,3 +58,29 @@ def test_handle_dovecot_request(db):
     assert userdata["home"] == "/home/vmail/some42@c3.testrun.org"
     assert userdata["uid"] == userdata["gid"] == "vmail"
     assert userdata["password"].startswith("{SHA512-CRYPT}")
+
+
+def test_100_concurrent_lookups(db):
+    num = 100
+    dbs = [Database(db.path) for i in range(num)]
+    print(f"created {num} databases")
+    results = queue.Queue()
+
+    def lookup(db):
+        try:
+            lookup_passdb(db, "something@c1.testrun.org", "Pieg9aeToe3eghuthe5u")
+        except Exception:
+            results.put(traceback.format_exc())
+        else:
+            results.put(None)
+
+    threads = [threading.Thread(target=lookup, args=(db,), daemon=True) for db in dbs]
+
+    print(f"created {num} threads, starting them and waiting for results")
+    for thread in threads:
+        thread.start()
+
+    for _ in dbs:
+        res = results.get()
+        if res is not None:
+            pytest.fail(f"concurrent lookup failed\n{res}")
diff --git a/tests/conftest.py b/tests/conftest.py
index 8d8f0227..b81ab8d4 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -9,9 +9,10 @@ import itertools
 from email.parser import BytesParser
 from email import policy
 from pathlib import Path
-from math import ceil
 import pytest
 
+from chatmaild.database import Database
+
 
 conftestdir = Path(__file__).parent
 
@@ -71,7 +72,7 @@ def pytest_report_header():
 
 @pytest.fixture
 def benchmark(request):
-    def bench(func, num, name=None):
+    def bench(func, num, name=None, reportfunc=None):
         if name is None:
             name = func.__name__
         durations = []
@@ -80,7 +81,7 @@ def benchmark(request):
             func()
             durations.append(time.time() - now)
         durations.sort()
-        request.config._benchresults[name] = durations
+        request.config._benchresults[name] = (reportfunc, durations)
 
     return bench
 
@@ -101,7 +102,9 @@ def pytest_terminal_summary(terminalreporter):
     headers = f"{'benchmark name': <30} " + fcol(float_names)
     tr.write_line(headers)
     tr.write_line("-" * len(headers))
-    for name, durations in results.items():
+    summary_lines = []
+
+    for name, (reportfunc, durations) in results.items():
         measures = [
             sorted(durations)[len(durations) // 2],
             min(durations),
@@ -110,13 +113,31 @@ def pytest_terminal_summary(terminalreporter):
         line = f"{name: <30} "
         line += fcol(f"{float: 2.2f}" for float in measures)
         tr.write_line(line)
+        vmedian, vmin, vmax = measures
+        for line in reportfunc(vmin=vmin, vmedian=vmedian, vmax=vmax):
+            summary_lines.append(line)
 
+    if summary_lines:
+        tr.write_line("")
+        tr.section("benchmark summary measures")
+        for line in summary_lines:
+            tr.write_line(line)
 
 @pytest.fixture
 def imap(maildomain):
     return ImapConn(maildomain)
 
 
+@pytest.fixture
+def make_imap_connection(maildomain):
+    def make_imap_connection():
+        conn = ImapConn(maildomain)
+        conn.connect()
+        return conn
+
+    return make_imap_connection
+
+
 class ImapConn:
     AuthError = imaplib.IMAP4.error
     logcmd = "journalctl -f -u dovecot"
@@ -157,6 +178,16 @@ def smtp(maildomain):
     return SmtpConn(maildomain)
 
 
+@pytest.fixture
+def make_smtp_connection(maildomain):
+    def make_smtp_connection():
+        conn = SmtpConn(maildomain)
+        conn.connect()
+        return conn
+
+    return make_smtp_connection
+
+
 class SmtpConn:
     AuthError = smtplib.SMTPAuthenticationError
     logcmd = "journalctl -f -t postfix/smtpd -t postfix/smtp -t postfix/lmtp"
@@ -202,6 +233,14 @@ def gencreds(maildomain):
     return lambda domain=None: next(gen(domain))
 
 
+@pytest.fixture()
+def db(tmpdir):
+    db_path = tmpdir / "passdb.sqlite"
+    print("database path:", db_path)
+    return Database(db_path)
+
+
+
 #
 # Delta Chat testplugin re-use
 # use the cmfactory fixture to get chatmail instance accounts
@@ -272,7 +311,7 @@ class Remote:
         self.sshdomain = sshdomain
 
     def iter_output(self, logcmd=""):
-        getjournal = f"journalctl -f" if not logcmd else logcmd
+        getjournal = "journalctl -f" if not logcmd else logcmd
         self.popen = subprocess.Popen(
             ["ssh", f"root@{self.sshdomain}", getjournal],
             stdout=subprocess.PIPE,
diff --git a/tests/online/test_0_login.py b/tests/online/test_0_login.py
index 929c59b0..86319e54 100644
--- a/tests/online/test_0_login.py
+++ b/tests/online/test_0_login.py
@@ -1,5 +1,6 @@
 import pytest
-import smtplib
+import threading
+import queue
 
 
 def test_login_basic_functioning(imap_or_smtp, gencreds, lp):
@@ -23,7 +24,7 @@ def test_login_basic_functioning(imap_or_smtp, gencreds, lp):
     with pytest.raises(imap_or_smtp.AuthError):
         imap_or_smtp.login(user, password + "wrong")
 
-    lp.sec(f"creating users with a short password is not allowed")
+    lp.sec("creating users with a short password is not allowed")
     user, _password = gencreds()
     with pytest.raises(imap_or_smtp.AuthError):
         imap_or_smtp.login(user, "admin")
@@ -40,3 +41,30 @@ def test_login_same_password(imap_or_smtp, gencreds):
     imap_or_smtp.login(user1, password1)
     imap_or_smtp.connect()
     imap_or_smtp.login(user2, password1)
+
+
+def test_concurrent_logins_same_account(
+    make_imap_connection, make_smtp_connection, gencreds
+):
+    """Test concurrent smtp and imap logins
+    and check remote server succeeds on each connection.
+    """
+    user1, password1 = gencreds()
+    login_results = queue.Queue()
+
+    def login_smtp_imap(smtp, imap):
+        try:
+            imap.login(user1, password1)
+        except Exception:
+            login_results.put(False)
+        else:
+            login_results.put(True)
+
+    conns = [(make_smtp_connection(), make_imap_connection()) for i in range(10)]
+
+    for args in conns:
+        thread = threading.Thread(target=login_smtp_imap, args=args, daemon=True)
+        thread.start()
+
+    for _ in conns:
+        assert login_results.get()
diff --git a/tests/online/test_2_deltachat.py b/tests/online/test_2_deltachat.py
index 8fa358ff..c1802704 100644
--- a/tests/online/test_2_deltachat.py
+++ b/tests/online/test_2_deltachat.py
@@ -91,7 +91,7 @@ class TestEndToEndDeltaChat:
 
         lp.sec("setup encrypted comms between ac1 and ac2 on different instances")
         qr = ac1.get_setup_contact_qr()
-        ch = ac2.qr_setup_contact(qr)
+        ac2.qr_setup_contact(qr)
         msg = ac2.wait_next_incoming_message()
         assert "verified" in msg.text