I've noticed that is as an old issue that never has been resolved proberly here on the forum. Let's give it a one more try 
I'm trying to get postmaster, abuse and root to function proeprly and in a supportet way by the system (SM).
abuse and root don't seem to be supported (like postmaster) by SM.
I've set the "Postmaster mailbox" field (undir General settings -> Server info) to both the admin@some-domain.com and someuser@some-domain.com. Neither of them seem to work.
When I send an email to postmaster, abuse and root @some-domain.com and look through the smtp log I see the following messages:
17:20:42 [66013] Delivery started for some-user@some-domain.com at 5:20:42 PM
17:20:57 [66013] Skipping spam checks: User authenticated
17:20:57 [66013] Starting local delivery to abuse@some-domain.com
17:20:57 [66013] Delivery for some-user@some-domain.com to abuse@some-domain.com has completed (Bounced)
17:20:57 [66013] Delivery for some-user@some-domain.com to abuse@some-domain.com has completed (Bounced)
17:20:57 [66013] Starting local delivery to root@some-domain.com
17:20:57 [66013] Delivery for some-user@some-domain.com to root@some-domain.com has completed (Bounced)
17:20:57 [66013] Delivery for some-user@some-domain.com to root@some-domain.com has completed (Bounced)
17:20:57 [66013] Starting local delivery to postmaster@some-domain.com
17:20:57 [66013] Delivery for some-user@some-domain.com to postmaster@some-domain.com has completed (Deleted) Filter: None
17:20:57 [66013] End delivery to postmaster@some-domain.com
17:20:57 [66013] Delivery finished for some-user@some-domain.com at 5:20:57 PM [id:248355766013]
As you can see the abuse and root are not supported, without createing a user or alias.
Also my postmaster email doesn't work (even though it says "completed"), instead I get the cryptive message "Deleted" and "Filter: None". What in the world does that mean?
A little more information in the help files would be greatly appreciated 
Any help would be greately appreciated!
Thanks,
H