ActionMailbox direct e-mail replies

[andreibondarev]

For one of my project, I'm implementing direct e-mail replies by using the new ActionMailbox framework. The recipient replies directly to the Thredded e-mail notification and that post gets automatically created in the topic. What is the appetite for having this functionality live in the thredded gem itself? I can try and put a PR together.

[glebm]

This would be very cool!

[jayroh]

I had had this in an OLD OLD version of this codebase and that implementation was slapped together with spit and duct tape.

Would be great to see this with a nice abstraction like ActionMailbox :)

[seabornhq]

@andreibondarev @glebm may take a shot at this?