Email queue not deleting undeliverable emails + MS Support Incident

[Clockworks]

Our email has a queue system that splits email as 1 (priority), 5 (medium), 10 (bulk). Problem is, a lot of clients put down fake emails/names that have no destination. We set it up as after 24 hours, the email should be deleted. Problem is, it stops trying to send the emails after 24 hours but they still remain in the queue, overflowing the damn thing with tens/hundreds of gigs. After scouring the internet for more info (and failing), I figured that either two things can happen:

- I post on forums asking for more help
- I post on forums asking for the Microsoft Support Incident and how the process works (can this be part of the technet package?)

Help?

EDIT: We are using MS SMTP Server on Server 03 and 08