Let.ter: Email Writing App on the Mac

I recently discovered a $4 Mac utility, Let.ter, that gives you a clean little interface to write and send emails in Markdown. There is no email interface, no inboxes to clear, and none of the other trappings of email. Just write a message and send it. In its current iteration it only works from one email account but I really like the idea of sending out email without having to deal with (or even see) all of the other correspondence the world is sending my way.