Multiple SMTP Based On Destination

I've been experiencing problems sending email to AOL using my own SMTP server. It seems, because my reverse DNS doesn't translate to my domain name (I'm hosted by someone else), AOL refuses to talk to my mail server. That makes those authentication emails impossible for AOL users. The workaround, of course, is to use Gmail's SMTP server to send them, as described here:

http://lifehacker.com/software/email-apps/how-to-use-gmail-as-your-smtp-...

While this works, I'd really rather use my own domain email address to send out the mails. Having said that, I really don't mind if AOL users see my gmail address as opposed to my own domain address.

What I'd like to see is an option that says "if the destination address is at such-and-such domain, use the following SMTP server to send it."

Is that doable? Does anyone else want it?

Thanks!