If you see the error:
Trying 127.0.0.1... Connected to localhost.localdomain. Escape character is '^]'. * BYE Service not available localhost.localdomain IMAP4rev1 2003.339 at Fri, 9 Mar 2007 23:09:15 -0700 (MST) Connection closed by foreign host.
Then delete your /etc/nologin file.