iPhone and personal domain name email

I have my own domain name (wow!!) and I use it for my primary email, as does my brother. He scored an iPhone as an early Christmas present, and I was wondering if it would be possible to push email to the phone when he receives an email to the domain name.

I am using exim on a dedicated host that I run, so I should have all of the authority I need to config it, I just don't know where to start. Thanks in advance everyone.