Domain forwarding

[Nunners]

I have a main domain (domain.co.uk) which has everything setup, including hosting, email accounts etc.

I also have a number of other domains (domain.com, domain2.co.uk) which I want to alias domain.co.uk - i.e. everything website/email etc gets forwarded to domain.co.uk

I have done this on the website side using the Plesk CP, however I can't work out how to setup the email side of things. I've got all the email accounts setup on domain.co.uk, but not on the alias domains - do I have to?

Cheers
Nunners