I have setup a test account on exchange 2013. I am unable to connect to the server via imap (server unavailable) I am however able to connect via outlook anywhere, when I do connect the outlook client connects with a GUID returned. I can send mail but cannot receive mail, the received mail is visible in the server queue.
Microsoft Exchange IMAP4 service on CAS role and the Microsoft Exchange IMAP4 Backend service on Mailbox role.
2. Use EXRCA to test your IMAP settings and check if any errors.
Is this issue only for Exchange 2013 user or for all users?
You common name and autodiscover pointing to Exchange2010 or 2013?