The mailing list for listmasters using Sympa

["Peter Polkinghorne (Staff)" <address@concealed>]

Here is an update with better, but still not perfect Exim configuration. 
These fix 2 problems:

a) Forgetting about the fact that with a local_part_prefix, Exim by default 
strips the prefix. Thanks to Marco for pointing this out.

b) bounce+somestuff messages should be delivered to sympa@robot_domain not 
bounce+somestuff@robot_domain.

Here is my stripped down but better Exim router & transport:

sympa_bouncequeue_aliases:
  debug_print = "R: sympa bouncequeue aliases for 
${local_part_prefix}${local_part}@$domain"
  driver = accept
  domains = +local_domains
#  local_parts = bounce : abuse-feedback-report
  local_part_prefix = bounce+
  transport = sympa_bounce_queue_transport
  no_more

Note abuse-feedback-report is dealt with by aliases.

sympa_bounce_queue_transport:
    driver = pipe
    command = /usr/lib/sympa/bin/bouncequeue sympa\@$qualify_domain
    user = sympa
    group = sympa
    return_fail_output
    return_path_add

Note for me $qualify_domain if the robot_domain.

This works up to a point, here is relevant Exim log with listname Xed out:

2023-04-19 12:30:32 1pp61A-0005Lb-1j ** 
address@concealed 
<address@concealed> R=sympa_bouncequeue_aliases 
T=sympa_bounce_queue_transport: Child process of sympa_bounce_queue_transport 
transport returned 127 (could mean unable to exec or command does not exist) 
from command: /usr/lib/sympa/bin/bouncequeue

So VERP reports are not processed quite right. However NDR reports (sent to 
list-owner@robot_domain) do.

I am also still baffled why some delivery failures are sent using VERP, while 
others use NDRs. I have no VERP set up at all.

Hoping for suggestions, as bouncequeue not logging anything on this failure 
and documentation not that detailed.

Peter Polkinghorne
Senior Systems Officer (Storage and Virtualisation)
T +44(0)1895 267070 | E address@concealed
Brunel University London
Information Services
Brunel University London, Uxbridge, UB8 3PH, United Kingdom
T +44(0)1895 274000
www.brunel.ac.uk
Connect with the University on Facebook, Twitter, LinkedIn, Google+, Instagram
Please note for the moment, I am working from home apart from Tuesday & 
Wednesday and am working 4 days a week, with my day off being Thursday 
usually.

-----Original Message-----
From: address@concealed <address@concealed> On Behalf Of 
Marco Gaiarin
Sent: 13 April 2023 21:00
To: Peter Polkinghorne (Staff) <address@concealed>
Cc: address@concealed
Subject: Re: [en@sympa] Sympa, exim and bounce...

Mandi! Peter Polkinghorne (Staff)
  In chel di` si favelave...

> The suggested Exim set up is wrong.
> I have the following, which still does not quite work properly:
> 
> # Sympa generic aliases for "bounce" and "abuse-feedback-report"
> # Added by Peter Polkinghorne 29/3/2023 # Modified to be better - pjmp 
> 31/3/2023
> sympa_bouncequeue_aliases:
>   debug_print = "R: sympa bouncequeue aliases for $local_part@$domain"
>   driver = accept
>   domains = +local_domains
> #  local_parts = bounce : abuse-feedback-report
>   local_part_prefix = bounce+
>   transport = sympa_bounce_queue_transport
>   no_more
> 
> And
> 
> # Sympa transport for bouncequeue program # Added by Peter 
> Polkinghorne 29/3/2023
> sympa_bounce_queue_transport:
>     driver = pipe
>     command = /usr/lib/sympa/bin/bouncequeue ${local_part}\@$domain
>     user = sympa
>     group = sympa
>     return_fail_output
>     return_path_add
> 
> Not sure why not working. Gets sent but nothing actually happens.

Looking at, seems that the transport misses a '${local_part_suffix}' in 
command...


> Also not sure why some bounce messages generated (using VERP which is not 
> enabled) where as some arrive as NDRs and get processed OK.
> So I have bounces coming back and submitted to Sympa but not processed. 
> This simply means bounces are unrecorded, which is annoying, but not too 
> bad from a service point of view.

Seems intended, look at:

        https://www.sympa.community/manual/customize/bounce-management.html

 VERP
 VERP (Variable Envelop Return Path) is used to ease automatic recognition of 
subscribers email addresses when receiving a bounce. If VERP is enabled, the 
subscriber address is encoded in the return path itself, so that the Sympa 
bounce management process (bounced) will use the address the bounce was 
received for to retrieve the subscriber email. This is very useful because 
sometimes, non delivery report do not contain the initial subscriber email 
address but an alternative address where messages are forwarded. VERP is the 
only solution to detect automatically these subscriber errors. However, the 
cost of VERP is significant, indeed VERP requires to distribute a separate 
message for each subscriber and breaks the bulk emailer grouping optimization.
 In order to benefit from VERP and keep the distribution process fast, Sympa 
enables VERP only for a share of the list members. If verp_rate is 10%, then 
after 10 messages distributed in the list all subscribers have received at 
least one message where VERP was enabled. Later, distribution message enables 
VERP also for all users where some bounces were collected and analyzed by the 
previous VERP mechanism.
 If VERP is enabled, the format of the messages return path are as follows:
   Return-Path: <bounce+user==a==userdomain==listname@listdomain>
 Note that you need to set a mail alias for the generic bounce+* alias (see 
???Addresses by mail domain???).

so seems that VERP is enabled but used on 10% of subscrivers at a time.

--
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