You wrote: "I'm starting to feel like I should just code something myself". It's exactly my feeling some time ago! And I also managed to stay lazy.
But the big differences in our approaches are technical details. I'd like to introduce MailML, a format for specifying the structure in mail messages. The possible logical blocks are titles, attachments, cites, signatures, urls, addresses and other. The MailML documents can be stored in XML database and queried through the web, something like Syntaco (http://www.syncato.org/). It should be an ultimately powerful system.
I sure it's a business opportunity. But I don't have time to try it. Unfortunately.