I got this weird problem one some of the users of our exchange server. When using mailbox, they are able to send messages without delay. But when using pst, messages to send gets stuck in outbox. And outlook has this popup box saying "Outlook is trying to retrieve data from the MS Exchange Server aaa.bbb.com"
I've done some googling and none of those suggested did not help. No firewalls are installed on the user's PCs.
- check AV for any rule blocking emails.
I've run out of ideas.
I hope somebody could help in this forum.