Rex, when you create a new domain in plesk after you type in the domain you want to create in the text field click next and then you will have 3 radio button options:
Physical hosting
Standard forwarding )select this one and type the domain name you want to be forwarded to in there)
Frame forwarding
I have two domains hosted on the same server, abc.com and abc.co.uk, I have to make abc.co.uk as the primary domain but want to use the mailbox of abc.com. I also want to redirect abc.com to abc.co.uk.
I have two domains hosted on the same server, abc.com and abc.co.uk, I have to make abc.co.uk as the primary domain but want to use the mailbox of abc.com. I also want to redirect abc.com to abc.co.uk.
You can create domain abc.com with mail service and domain alias abc.co.uk with enabled Web and Mail options. Unfortunately you cannot do the reverse because the mailboxes will be available via POP or IMAP only as @abc.co.uk.