@superboyac: Trust me, I'm not that sharp ;p.
our only real "external" issue is triggering the activity from a received email. With a product like Filemaker and AlphaFive you ask (and search) on their forums and you probably get a few good answers. Should be fairly easy, a lot depends on the email product used (Note: Filemaker may have some email integration/hooks.) Let's say you use Eudora but prefer Thunderbird or TheBat! for this app. You should be able POP-ify a Gmail account so that you could work that account with Thunderbird/Bat so you do not have to change your own personal email preference. "Pushing" the email response should be fairly simple, built in to the product (one of the reasons you purchase an environment instead of simply doing more basic raw code, as in a scripting language).
-Steven Avery
I advise against using a mechanism such as this. It is better to have the server send the response email than some POP3 client handling a rule. It is extremely easy to code, perhaps easier than setting up a local client in many ways, and the server is more likely to be 'always up'. Well, this should be the obvious superior solution. For many, it is simply taking a step into something you've not done before. You'll find it is *very* easy to send an email from your server via PHP (or other) though. Just my two cents.
Even events that require file manipulation should be done on the server, and - again - ironically can often easier be done there. PHP and other scripting languages have grown so robust that you can do more with them than the 'rules' of any email client, that's for sure