Another point to consider: You could do something similar to Yahoo! Groups / eGroups where the to field determines where it goes. e.g. This forum is called vBulletin Code Hacks. To send a post via email to it, address the email to vbulletin_code_hacks@vbulletin.com and that would help sort them on the way in. For a site with hundreds of forums (ascifi.com comes to mind), that could either be a help (pre-sorting makes it a little more efficient) or a hinderance (too many addresses to keep track of), but for a site like this or like SPF, it wouldn't be too bad.