Recently we have upgraded JIRA to 6.4.11 and found users unable to create issues and adding comments now. Incoming emails features used to be working on previous JIRA version 6.2.
I have enabled jira incoming debug logs and found the following debug log content. Incoming mail server configuration(IMAP) is successful and I am able to telnet mail server port.
2015-10-07 12:19:44,123 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG IMAP: AUTH: NTLM
2015-10-07 12:19:44,123 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG IMAP: AUTH: GSSAPI
2015-10-07 12:19:44,123 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG IMAP: AUTH: PLAIN
2015-10-07 12:19:44,123 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG: protocolConnect login, host=imap.xxxxx.com, user=jira, password=<non-null>
2015-10-07 12:19:44,123 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG IMAP: LOGIN command trace suppressed
2015-10-07 12:19:44,185 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG IMAP: LOGIN command result: A1 OK LOGIN completed.
2015-10-07 12:19:44,185 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa A2 CAPABILITY
2015-10-07 12:19:44,186 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa * CAPABILITY IMAP4 IMAP4rev1 AUTH=NTLM AUTH=GSSAPI AUTH=PLAIN STARTTLS UIDPLUS CHILDREN IDLE NAMESPACE LITERAL+
A2 OK CAPABILITY completed.
2015-10-07 12:19:44,186 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG IMAP: AUTH: NTLM
2015-10-07 12:19:44,187 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG IMAP: AUTH: GSSAPI
2015-10-07 12:19:44,187 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG IMAP: AUTH: PLAIN
2015-10-07 12:19:44,187 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa A3 LOGOUT
2015-10-07 12:19:44,188 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa * BYE Microsoft Exchange Server 2010 IMAP4 server signing off.
A3 OK LOGOUT completed.
2015-10-07 12:19:44,188 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG: IMAPStore connection dead
2015-10-07 12:19:44,188 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG: IMAPStore cleanup, force false
2015-10-07 12:19:44,188 DEBUG [IMAP Mail Server] http-bio-8080-exec-59 spatruni 739x50364x1 tzx7hs 10.67.64.105,10.15.224.34 /secure/admin/VerifyPopServerConnection!update.jspa DEBUG: IMAPStore cleanup done
