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

[Rick Romero]

  Quoting Oscar del Rio <delrio at mie.utoronto.ca>:

> 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) :

Any domain hosted by RackSpace will reject a NULL sender for
'backscatter'. 

Bascially, 'backscatter' blockers assume all edge SMTP servers will have
complete knowledge of the final delivery status - during the SMTP
conversation - thus labeling all NULL senders as forged spam redirected to
them via a bounce message. 

http://www.backscatterer.org/

Rick