- Error code: 0x274c - In my case, the IMAP service was disabled on back end server.
- Error code: 0x52e - In my case, this problem was caused by a stopped IMAP service on a Back-End server in a BE/FE scenario (SSL forced on FE).
- Error code: 0x533 - In my case, the IMAP4 protocol was disabled for this user in the Exchange Features tab of the user's Properties window in Active Directory Users and Computers.
- Error code: 0x274d - We received this event, with Error code 0x274d
when trying to test IMAP with test accounts. We are using a FE/BE configuration and it turned out that the Microsoft Exchange IMAP service was not started on the BE server.
This problem is similar to the POP3 logon issue. I modified the Exchange alias to match the pre-windows 2000 logon attribute and then I was able to logon successfully.