diff --git a/online-tests/benchmark.py b/online-tests/benchmark.py
index 3e2e90b1..4a7bb551 100644
--- a/online-tests/benchmark.py
+++ b/online-tests/benchmark.py
@@ -19,6 +19,7 @@ def test_tls_smtp(benchmark, smtp):
 
     benchmark(smtp_connect, 10)
 
+
 def test_login_smtp(benchmark, smtp, gencreds):
     def smtp_connect_and_login():
         smtp.connect()
@@ -39,3 +40,17 @@ def test_send_and_receive_10(benchmark, cmfactory, lp):
             ac2.wait_next_incoming_message()
 
     benchmark(send_10_receive_all, 1)
+
+
+def test_ping_pong(benchmark, cmfactory, lp):
+    """send many messages between two accounts"""
+    ac1, ac2 = cmfactory.get_online_accounts(2)
+    chat = cmfactory.get_accepted_chat(ac1, ac2)
+
+    def ping_pong():
+        chat.send_text("ping")
+        msg = ac2.wait_next_incoming_message()
+        msg.chat.send_text("pong")
+        ac1.wait_next_incoming_message()
+
+    benchmark(ping_pong, 5)
diff --git a/online-tests/conftest.py b/online-tests/conftest.py
index 8abde3d1..a4696698 100644
--- a/online-tests/conftest.py
+++ b/online-tests/conftest.py
@@ -68,9 +68,10 @@ def benchmark(request):
         for i in range(num):
             now = time.time()
             func()
-            durations.append(time.time()-now)
+            durations.append(time.time() - now)
         durations.sort()
         request.config._benchresults[name] = durations
+
     return bench
 
 
@@ -84,7 +85,6 @@ def pytest_terminal_summary(terminalreporter):
         tr.write_line(f"{name: <30} {median:2.4f} seconds")
 
 
-
 @pytest.fixture
 def imap(maildomain):
     return ImapConn(maildomain)