diff -r de81e0fe4905 Lib/imaplib.py
--- a/Lib/imaplib.py	Sun Mar 02 20:29:18 2014 +0100
+++ b/Lib/imaplib.py	Mon Mar 03 00:33:44 2014 +0100
@@ -165,7 +165,7 @@
     class abort(error): pass        # Service errors - close and retry
     class readonly(abort): pass     # Mailbox status changed to READ-ONLY
 
-    def __init__(self, host = '', port = IMAP4_PORT):
+    def __init__(self, host = 'localhost', port = IMAP4_PORT):
         self.debug = Debug
         self.state = 'LOGOUT'
         self.literal = None             # A literal argument to a command
@@ -1205,7 +1205,7 @@
         """
 
 
-        def __init__(self, host='', port=IMAP4_SSL_PORT, keyfile=None, certfile=None, ssl_context=None):
+        def __init__(self, host='localhost', port=IMAP4_SSL_PORT, keyfile=None, certfile=None, ssl_context=None):
             if ssl_context is not None and keyfile is not None:
                 raise ValueError("ssl_context and keyfile arguments are mutually "
                                  "exclusive")