[Dovecot] RFE: please add Return-Path: to sieve sent mail headers

[Oscar del Rio]

On 05/13/14 03:02 PM, Stephan Bosch wrote:
>
> Use of NULL envelope sender is generally recommended to prevent mail loops

Unfortunately, many servers out there reject emails with NULL sender.
Some recent examples (real server names edited) :

... while talking to antispam1.*.ca.:
  >>> DATA
  <<< 550 Empty envelope senders not allowed

... while talking to smtp.*.net.:
  >>> MAIL From:<> SIZE=1096
  <<< 550 5.1.0 <> Blank From: addresses are not allowed. Please provide 
a valid From: IB501 <http://x.co/srbounce>

... while talking to spam.*.edu.cn.:
  >>> DATA
  <<< 553 Requested action not taken: NULL sender is not allowed

... while talking to mail.*.co.kr.:
  >>> MAIL From:<>
  <<< 501 bad sender address expression.

... while talking to antispam.*.com.:
  >>> MAIL From:<>
  <<< 501 Syntax error in address