ActionMailbox support for postal ignest

Hi,

Postal is a open source alternative to services like Mailgun. Postal is written in RoR.

I am in no way affiliated with Postal but find it strange that postal is not a out-of-the-box supported ActionMailbox ingest provider.

I would like to implement this option and contribute it to Rails. Any interest in such a PR?

Interesting. Could you consider to create a separate gem for this?

That was mi initial thought, but thought it would be nice to have it in core. Alas, separate gem it is.