OTRS fails to fetch emails from a mailbox on Exchange 2013

[danieldai]

We upgraded our mail server from Exchange 2007 to 2013 last weekend. When we returned back to work, we found OTRS fails to fetch mails from the migrated mailbox. All incoming emails stays in Inbox folder. When I manually fetch in Admin - Mail Account Management, it simply shows "Finished" without returning any error message in Admin - System Log.

BTW, that mailbox type is IMAP in OTRS. This have worked perfectly when the mailbox was on Exchange 2007. I am wondering if there is something to be set up or changed in the mailbox on Exchange 2013. Thanks in advance.

[jojo]

check the logs of the Exchange
also check if IMAP or IMAPS has to be used