masked “forwarding” email?

Is it possible to apply masked web forwarding to an entire domain?

For example, if I have domain.com and I want dom.com to point to it, that’s fine for web pages and such…

But if I have an email account a@domain.com, I want to be able to write an email to a@dom.com and have it show up in my a@domain.com account.

I need to do this WITHOUT getting my host involved, as they will charge me to host a second domain. I also do not want to get into hosting dom.com on a seperate server and individually forwarding each user’s email seperately from dom.com to domain.com as that becomes a nightmare when you have 200 users.

I have full DNS control of both domains in question.