DNP does not correctly handle mail forward (aliases) and mail groups in Merak. Rather than create a mail alias as true forwarding account (which can be done using the API), instead it creates it as a mailbox with a forwarding. As a result, mail collects in the mailbox that the client will never pick up - because they will never log in to the account. This is massively wasteful on a server level.
An additional error associated with this is that DNP won't import Merak resources correctly. It imports forwarders and mailboxes - which they aren't. DNP support told me they 'can't differentiate' during the import. But, this simply isn't true at all - the Merak API clearly allows differentiation between email addresses and forwarders (aliases).
The same is true of mail groups - which Merak has a set assignment for but which DNP creates as a mailbox with multiple forward addresses.
I have repeatedly asked for this to be fixed but get no response otehr than either it's not possible (which isn't true) or it is correct functionality (which also isn't true).
Meanwhile, in the meantime I've calculated that in the 6 months since I started actively using DNP my server has wasted around 5GB of disk space through this incorrect allocation. I have also been unable to migrate from my previous control panel because the import process doesn't work correctly.
So, if you read this and are thinking of using DNP with Merak, BEWARE - and make sure you have a LOT of space disk space on your mail servers!!