Create a new mail account and give it a name: Sales Department. Assume that all orders and sales support messages will be delivered to this mailbox.
Let us set the mailbox to be checked for new messages automatically once per 30 minutes.
Now create a special rule that will be applied to all incoming messages. It will sort out messages addressed to the sales department (i.e. to addresses containing sales@my_comp); all messages whose To field does not contain sales@my_comp will be simply deleted:
This rule will be applied to all messages that are in the Sales Department mailbox when they are received.
Now you can view messages delivered from our mailbox in the Messages form (Services -> Mail -> Messages):