I actually have 2 outgoing servers configured.
cwmx.com for 3g times, and mail.charter.net (my home isp) for when I'm on home wi-fi.
When on wi-fi, it *might* send, but it can take a very long time. I'm guessing it has to fail out of trying the cwmx.com before it rolls over to try the other one.
I hoped there was a better way of setting this up so that it always works - I don't know how it would react if I'm on a wi-fi network other than at home.
I have thought about the gmail solution, but haven't tried it yet.