Allow __returnpath__ routing to go to other endpoint types

[adamcooke]

At present is is restricted to HTTP endpoints but there's no real reason why it can't forward to other email addresses or SMTP servers if such behaviour is desired.

[influenist]

Any update on this matter. Routing to HTTP is not workable solution for SMTP platforms. The sender wishes to be notified in their inbox. Login in to Postal or HTTP platform is a non-workable solution.

[saporus]

Any update on this matter? This is very important.

Thanks