No, that's not at all what I want. To access received mail, I know how to use pop3 and it works perfectly well regardless of how many computers you're accessing the mail with. The only caveat is that each computer will have its own unique copy of the message. Not necessarily a bad thing, depending on how you want to deal with the mail. I also thought that mail stored locally on the iPhone (regardless of what transport was used to send it) would sync back to the Mac with iTunes.

What I want, is to be able to sync back to my Mac all email I generate on the iPhone.

Since iTunes doesn't appear to do mail sync, which I thought it did, it appears my only option is to use imap on both the iPhone and my desktop for that account. That will allow my desktop to download the sent/generated messages from the server on its own.

The problematic aspect isn't necessarily an imap issue. But simply an issue of leaving that much content on the mail server, potentially making the people who run the server non-to-pleased. I recall getting warnings from the Dreamhost server with my support address when it was well below 1.2GB. I'm going to look at the mail settings to see what I can do about my quotas.

My big issue right now is that I have a local inbox on my Mac with about 2800 messages in it for that email account. If I drag them into the new account setup (for imap) it's going to copy them all to the server and then I'll have to download them all again. I suppose that's the only way to get through this unless I just want to dump them into a different local folder such as "older mail" or some such.