More seriously, if you're looking to invent a better UI for an email client, you might find it easier to build it first as an add-on for Thunderbird. This would get you a working prototype without having to worry about the nuts-and-bolts problems that you'll face if you start from scratch. You could use this to hammer the kinks out of your concept with reasonably little coding effort. Even if you don't want to use Thunderbird in the end, it would help you find out whether your idea will work and if it is worth the effort of reading all those bloody RFCs.
