I wanted to pass messages from lilac to Jabber, since I don't run a mail server. There was one archived project like that on GitHub, written in Go using an XMPP library that was wiped off the face of the internet a long time ago. I didn't want to bother the author of the library (who may or may not still have the code that he deleted from GitHub), and not knowing Go, I turned to Python. 'This can't be all that hard', I thought to myself. The result is this mess.
An extremely crude XMPP component that receives mail as a SMTP server and relays it to a specified set of XMPP users. Put together in a single morning and polished (yeah, right) in the afternoon.
Initially copied verbatim from "XMPP ToDo List Example", which seems to be a modified example from the SleekXMPP project. Supplemented with usage examples from aiosmtpd docs. Modified to accept a socket passed by systemd, since that allows us to listen on port 25 as an unpriviledged user.
Since the component example originally came from SleekXMPP, it's MIT-licensed, I guess? The receive_systemd_socket function is a modification of aiosmtpd.controller.InetMixin._create_server from aiosmtpd, and the MailHandler class was copied directly from their docs, their code is under Apache 2.0. I haven't published much code before, so if anyone gets outraged about the licensing - don't beat me too hard, contact me, and we'll clarify the situation.