The mailing list for listmasters using Sympa

[Steve Shipway <address@concealed>]

This is because Yahoo (and some others) now advertise a strict DMARC policy, 
which specifies that the From address should be validated against SPF.  Since 
this fails (due to the list redirection) the message is dropped.

This is a problem because DMARC does not take into account the 'secretary 
scenario', of which a mailing list is a particular use case (imagine a 
secretary sending an email on behalf of her boss; she is the Sender, but the 
message is From the boss).  Ironically, Sympa is strictly RFC822 (SMTP) 
compliant, which states that the From header must state the originator and 
the Sender header gives the message sender if different; but SPF and DMARC 
ignore Sender and assume From is the Sender, meaning it is impossible to be 
simultaneously compliant to both standards.

The solution is to munge the From address so that it no longer causes a DMARC 
check, either by setting the 'anonymous' option on the list so that 'From' is 
always set to some address you own, or else using the DMARC patch that was 
added after v6.1.22.  The DMARC patch allows Sympa to detect if a strict 
DMARC policy is in effect for the sender domain, and if so, munges the From 
address while preserving the Friendly Name.

There was extensive discussion on many fora last year complaining about the 
broken DMARC standard and the strict implementation used by Yahoo, AOL and 
others causing all mailing lists to break; however the only thing to do is to 
work around it as with this patch.

TL;DR -- use DMARC protection in Sympa 6.1.22 or later.

Steve

Steve Shipway
University of Auckland ITS
UNIX Systems Design Lead
address@concealed
Ph: +64 9 373 7599 ext 86487


________________________________________
From: address@concealed 
[address@concealed] on behalf of Radu Vatav 
[address@concealed]
Sent: Tuesday, 27 January 2015 3:55 a.m.
To: address@concealed
Subject: [sympa-users] how to distribute with list address in "From:" and 
original sender in "Reply-to"?

Hello,

yahoo changed policy and is not accepting mails with "From: "
someone@some_domain and delivery from another_domain. See here:

http://postmaster.yahoo.com/errors/postmaster-28.html

The only way I found that works is setting the list address as
anonymous_sender, but information about original sender is lost. Yahoo
suggests setting the original sender as "Reply-to" but I haven't managed
to do so in sympa.

I tried remove_headers with reply_to_header and some other combinations
I don't remember, the point is, if I remove the "From" field, it's lost
forever.

Any tips on how to do this?

Best regards,
Radu Vatav