We have a couple email accounts setup to forward email to a different domain; the email is then to be deleted upon forwarding. The thing is some email is not being forwarded and thus not deleted. The curious thing is much of this email is subscription-based (e.g. newsletters, promotional, etc.). I've looked at the headers on a few and it appears the recipient is clearly identified (as opposed to some generic distribution list), but again not all subscription-based email is failing to be forwarded.
Fortunately we still login to SmarterMail occasionally to check the spam folder, but I don't understand why this is happening.