[Coco] Bounces

[CoCoList for Color Computer Enthusiasts]

Dennis,

We have run into the same problem, on the systems we host.

However our emails were just disappearing, no bounces to give us a clue it was happening.

Customer implemented Dmarc and never told anyone.

John Strong
 

 
> Message: 1
> Date: Wed, 07 May 2014 07:50:47 -0400
> From: Dennis Bathory-Kitsz <dennis-ix at maltedmedia.com>
> Subject: [Coco] Bounces (definitive answer)
> To: cocoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Message-ID: <20140507115131.AF2092285C7 at mail01.trans-video.net>
> Content-Type: text/plain; charset="us-ascii"; format=flowed
> 
> 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.
> 
>