I tried something like this as well. I think that if you use aliases in this way the gmail account does not end up in the header of the message. At least not in a way that gmail can decipher. I haven't figured out a fix yet, but love to hear of one if someone has.

Basically the message gets aliased to gmail which thinks it is to name@domain.com, in your case, and has no matching user to deliver the message to (I think).

Michael Coyne
seaturtle.org