diff --git a/Lib/test/test_imaplib.py b/Lib/test/test_imaplib.py
index 32bfa11..1beb39e 100644
--- a/Lib/test/test_imaplib.py
+++ b/Lib/test/test_imaplib.py
@@ -187,6 +187,9 @@
     server_class = SecureTCPServer
     imap_class = IMAP4_SSL
 
+    def test_linetoolong(self):
+        raise unittest.SkipTest("test is not reliable on 2.7; see issue 20118")
+
 
 class RemoteIMAPTest(unittest.TestCase):
     host = 'cyrus.andrew.cmu.edu'