diff -Nru offlineimap-7.3.2.orig/offlineimap/imaplibutil.py offlineimap-7.3.2/offlineimap/imaplibutil.py
--- offlineimap-7.3.2.orig/offlineimap/imaplibutil.py	2020-03-24 15:55:29.921276712 +0000
+++ offlineimap-7.3.2/offlineimap/imaplibutil.py	2020-03-24 16:06:06.550428992 +0000
@@ -19,7 +19,6 @@
 import time
 import subprocess
 import threading
-import rfc6555
 import socket
 import errno
 import zlib
@@ -79,15 +78,8 @@
     def open_socket(self):
         """open_socket()
         Open socket choosing first address family available."""
-        if self.af == socket.AF_UNSPEC:
-            # happy-eyeballs!
-            return rfc6555.create_connection((self.host, self.port))
-        else:
-            return self._open_socket_for_af(self.af)
-
-    def _open_socket_for_af(self, af):
         msg = (-1, 'could not open socket')
-        for res in socket.getaddrinfo(self.host, self.port, af, socket.SOCK_STREAM):
+        for res in socket.getaddrinfo(self.host, self.port, self.af, socket.SOCK_STREAM):
             af, socktype, proto, canonname, sa = res
             try:
                 # use socket of our own, possiblly socksified socket.
diff -Nru offlineimap-7.3.2.orig/requirements.txt offlineimap-7.3.2/requirements.txt
--- offlineimap-7.3.2.orig/requirements.txt	2020-03-24 15:55:29.923276731 +0000
+++ offlineimap-7.3.2/requirements.txt	2020-03-24 16:06:15.584516249 +0000
@@ -2,4 +2,3 @@
 six
 gssapi[kerberos]
 portalocker[cygwin]
-rfc6555