[exim] Setting up Exim to handle multiple domains

I am trying to setup exim to be able to handle multiple domains using
exim and dovecot. I have found a couple of how tos, but they are not
very updated and I am struggling to get this completed.

I was wondering if anyone has done this and might have a good how to
available? I was hoping to use MySQL to store the usernames and
domains along with passwords. The mail will be stored as maildirs like
/maildir/domain/user.

If anyone has any suggestions or places to reasearch it would be
greatly appreciated.

Thanks,
-Eric