Add IMAP/POP3 receiver

[turt2live]

Still maintain the own mailserver support, and external push support. This would just be a built-in receiver method.

[turt2live]

Something like https://www.npmjs.com/package/imap or https://www.npmjs.com/package/imap-simple might be worthwhile for this sort of use case

[yoitcc]

Hello Travis,

we talked on matrix about the post_message.js, while reading up, I found https://www.npmjs.com/package/simple-node-imap-async , updated just a month ago, including support for gmail oauth.

I also did a little bit of writing (copy&pasting to be honest ;) and added preliminary support for IMAP. Surprisingly it successfully connects (and even spits out logs when a new mail arrives ^^), but this is all.
You can find it at https://github.com/yoitcc/matrix-email-bot-imap - please consider my experience with TypeScript started not even a day ago.

Hopefully this is interesting enough to note here, thanks again for all your work!
With best regards,
Oswald