Postfix question

Hi,

I am in the process of migrating my mail server qmail to postfix. But I am struggling to figure out how to implement some functionality using postfix. I have postfix up and running with virtual users and domains via sql and everything is working.

I host about 20 domains but I only have 3 that are really different. I have the three different domains setup but I am not sure how to create the aliased domains.

I have found lots of documentation on how to alias to individual mailboxes but not entire domains.

For example:

I want to alias everything that comes to domain1.com and domain2.com go to the same user on domain5.com.

So bob@domain1.com is aliased to bob@domain5.com and jane@domain2.com is aliased to jane@domain5.com. Except there are dozens of accounts like this and I don't want to have to do it individually.

I appreciate any advice anyone can provide.