[FEATURE] Per-user email devices

[JCBird1012]

Hello,

Is your feature request related to a problem?

It would be nice to tie email devices to a specific user, or permission them in such a way where certain users can only access certain email devices (i.e. selecting which users can access/send to any given device/alias) - this is a shift away from the current paradigm of email devices belonging to the Stump instance as a whole and being globally accessible.

I share my Stump with some (close) friends who have their own e-readers and enjoy the SMTP mailer feature, but as it stands, if I didn't trust them, they could spam my Kindle (or anyone else's Kindle) with any books they wanted.

[aaronleopold]

I really like this suggestion, thanks!