Empty envelope sender in mail notifications

[pboguslawski]

Feature Description

Mail notifications sent by Gitea (like info about being added to repo as collaborator, checked in v1.13) have nonempty envelope sender which may generate unnecessary bounces in case of delivery problems. Now address configured in

[mailer]
FROM = Name <address@example.com>

generates messages with

Return-Path: <address@example.com>
From: Name <address@example.com>

Consider setting empty envelope sender which is allowed i.e. for bounces to avoid loops

https://datatracker.ietf.org/doc/html/rfc5321#section-4.1.1.2

With empty envelope sender messages should contain

Return-Path: <>
From: Name <address@example.com>

Not sure but places to be modified are:

https://github.com/go-gitea/gitea/blob/main/services/mailer/mailer.go#L245
https://github.com/go-gitea/gitea/blob/main/services/mailer/mailer.go#L213

Screenshots

No response