I'm having trouble with inbound mail delivery.
It looks like a small amount of inbound mail isn't getting delivered to the correct mailboxes.
The only mailboxes being impacted are being polled by a service which pops them. I'm not sure if it's related.
To date, I've done the following.
I've verified with my filtering provider that the messages are being delivered to my mail server.
I set up a second box and have it set to mirror all inbound mail to the problem box (AD -> Primary account -> Forward & deliver to original boxes)
I've looked at the Event viewer. Nothing seemed out of the ordinary, but I did see some Event 9661s I didn't recognize.
I have message tracking enabled, as well as smtp logging enabled.
Where should I go from here to determine the cause of this behavior?