[Coco] Bounces (definitive answer)

[Dennis Bathory-Kitsz]

As I suspected, this is a DMARC issue, not an ISP hack.

The following excerpts are from pair Networks (which houses my server 
with some 40 websites as well as the maltedmedia CoCo FTP).

For now, until Mailman 2.1.18 is implemented, I'm changing the header 
so everything will appear to come from the CoCo list.


Hello Dennis,

Recently, large ISPs and free email providers started implemented a 
new email authentication method called 
DMARC(<http://www.dmarc.org>http://www.dmarc.org).

In the simplest terms, DMARC is specification for checking the domain 
of an email against a list of servers authorized to send email for 
that domain. For example, Yahoo provides a list of servers that are 
authorized for sending email. When an email host implements DMARC and 
receives an email from a Yahoo address, it checks the IP address of 
the server that it received the message from against the list of 
authorized Yahoo servers. If that IP is not found in the list the 
mail is rejected.

The unintended consequence here is with mailing lists such as your 
list. If someone with a yahoo address sends a message through the 
list, it appears as coming from their yahoo address. However, the 
pairList server is not on the list of authenticated servers that can 
send email for a yahoo address and as such any provider using DMARC 
will reject or bounce the message.

Currently the only work around available for your lists is to turn on 
the anonymous_list option. [...]

This sets the From header of the message to be that of the list 
rather than the senders address.

[...] we are in the early stages of upgrading all pairLists to 
Mailman 2.1.18 which was just released on May 3 and includes new 
features designed to address the issues that DMARC causes for mailing lists.




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