Dovecot Submission Proxy Auth

[Stephan Bosch]

Op 6-4-2018 om 13:52 schreef Paul Hecker:
> Hi,
>
> Dovecot 2.3.1 (8e2f634). Could not get Dovecot to forward the (plain) authentication to the SMTP server using submission. Reason why I need it is sender spoofing (do not want my employees to send messages in behalf of me).
>
> In exim I can disable sender spoofing with the authenticated user. When sending through dovecot, exim either does not accept the email (need auth) or relay every sender address (because relaying from localhost).
>
> Am I missing a setting or do I need any additional field in the (MySQL) user_query/password_query to forward the password?
>
> You can find my config here:
>
> https://gist.github.com/lluuaapp/7daddf761131da47237b0f45e6bab5a8

That would be possible using the following SMTP AUTH feature:

https://tools.ietf.org/html/rfc4954#section-5

Which is apparently supported by Exim: 
https://www.exim.org/exim-html-current/doc/html/spec_html/ch-smtp_authentication.html#SECTauthparamail
This requires explicit configuration, so it will not work out of the box.

The Dovecot Submission service should support this too. It sends an AUTH 
parameter with the MAIL command (currently only then the username is a 
valid SMTP address). However, I must say, I haven't tested this recently.

I can try this in a few days. Feel free to experiment with this yourself.

Regards,

Stephan.