Currently there are 10 mail queues in exchange. Over the last week we've noticed 15-20 delayed messages per day or from the server notifying us of delayed emails being sent, or not sent. Some eventually send, other do not send at all. We're unable to see a pattern; the delayed messages can happen on a newly created email, they can also happen in the middle of a correspondence after several mail exchanges have taken place. What causes this, and how do we fix this so it will not continue?
The problem appears to be very similar to this MS article and weve applied the fix yet were still experiencing the mail delay issues.