I've got a hosted exchange solution through Apptix, which isn't the problem, I think, but it may be relevant.
I have my main account, msimmons@mydomain.com, and to that, I have an alias, matt.simmons@mydomain.com.
Whenever I send an email to matt.simmons@mydomain.com, I examine the headers, and I see the "To:" field being correct, "To: matt.simmons@mydomain.com". All is well.
I recently set up another user, services@mydomain.com to function as a multipurpose mailbox. I aliased "nagios@mydomain.com" to the services account in the same method that I did "matt.simmons@mydomain.com", however nothing I have sent to "nagios@mydomain.com" actually goes TO "nagios@mydomain.com". All of the headers say "To: services@mydomain.com". This makes it extremely difficult to filter based on headers alone.
Does anyone have any feedback on what settings I would need to look at in order to fix that?