Allow changing SMTP provider without recompiling app

[DeanMarkTaylor (Dean Taylor)]

Existing topic here:

Allow update smtp settings in admin panel

Email is such a messy and buggy system, since i have to debug the email system problem once awhile, it would be convenient to provide an easy settings in admin panel. rather than to rebuild the whole docker app. I dont understand why email setting is a set-once option.

You might want to add your and comment there.