Are you having problems trying to get GMail and iPhone to play nicely? Colin has written up a great article detailing a solution that might work for you quite well. It isn’t as hard as it looks, just make sure to read carefully

Basically entails setting up a filter to ignore anything you don’t want on your iPhone (mailing lists for example), and forwarding the rest to an imap enabled server. Then your iPhone checks the incoming imap server, and you set your reply-to address desired. A few options are presented in Colin’s article to help you figure out the best solution.