[exim] Question about SRS

Top Page
Delete this message
Reply to this message
Author: Patrick Cernko
Date:  
To: exim-users
Subject: [exim] Question about SRS
Hi list,

after studying the documentation about SRS
(https://www.exim.org/exim-html-current/doc/html/spec_html/ch-dkim_spf_srs_and_dmarc.html#SECTSRS)
I have a problem understanding one detail:

Why is it required to set max_rcpt=1 in the remote_forwarded_smtp transport?

The documentation seems not to include any reasons, why you have to do
this for SRS forwards (explicitly).

I even found an example where this might be disturbing: Imagine a mail
alias based list with n recipients at the same external destination
domain (e.g. some freemailer). If some x recipients of them have e.g.
quota issues, the original sender will get x bounce messages. With
max_rcpt=100 (the default), the sender will get only one bounce with a
list of x failed recipients. This example is independent of SRS, however
if SRS is in use, the local MTA also has to deal with x bounces to be
forwarded back to the original sender.

Regards,
--
Patrick Cernko <pcernko@???> +49 681 9325 5815
Joint Scientific IT and Technical Service
Max-Planck-Institute für Informatik & Softwaresysteme