I have this problem with e-mail arriving to the destination in 1-2 hours.
What I’ve done so far …
Checked the “event viewer” for errors, very few and nothing out of ordinary.
Checked the counters in “performance console”, everything seems fine.
Cleaned the mail boxes.
Cleaned the queues and queue folder.
Defragmented mailbox and public folder store.
And…no results:( …
I have 1 exchange sever and around 60 users.