Campus Mailing List, Configuring your list for DMARC

How do I configure my list to rewrite the ‘sender’ and deliver the message ‘on behalf of’ XYZ?

NOTE: New Federal rules prevent the delivery of Federal email to forwarded accounts

Starting Oct 16, 2018 the U.S. Department of Homeland Security will fully implement a new directive relating to email delivery. Federal agencies are being mandated to follow Binding Operational Directive 18-01 to help ensure the integrity and confidentiality of Internet-delivered data. You will be impacted if you receive email from Federal agencies and your campus email is forwarded or redirected. If you use a mailing list for redistribution of email from federal agencies you will need to configure your list appropriately.


This file describes how the mail list server changes the From: field of an email to address enhanced email authentication policies defined by DMARC.    DMARC is a technical specification to help reduce email-based abuse and spam.  DMARC standardizes how email receivers authenticate email across organizations and email services such as Federal agencies AOL, Gmail, Yahoo, Hotmail, etc…  DMARC policies are published by organizations in the public DNS and are available so mail servers understand which domains enforce DMARC policies.  Information specific to the email provider is available from:

A side-effect of this standard authentication is the mismatch email list services create between the list and sender email addresses.  Many email servers mark list emails as mismatched and tag them with "p=reject” which prevents these emails from being delivered.   A primary goal of DMARC was to prevent spam that originates from a senders domain to be received by the same sender’s domain (e.g. AOL to AOL email, Yahoo to Yahoo, etc..)   The result is an AOL subscriber sending email to may get tagged as spam and other AOL subscribers will not receive the email posting.  

To comply with this new authentication mechanism, Sympa will rewrite the From: field with something that is acceptable to domains enforcing this DMARC policy.

Sympa DMARC Configuration

(Admin) > Edit List Config > DKIM – DMARC Protection

If your mail list has Yahoo, AOL, Gmail or Hotmail subscribers, you’ll need to configure DMARC to prevent AOL-to-AOL email from being tagged as spam.  The default settings are configured to address this situation.  The default settings are set so the Protection modes: apply to “all” email messages and rewrites the New From name format:  in the “email “via Mailing List”” format. 

The following section describes the different options that are available for the list owner to change based on their lists needs.

Input fields and Values

Protection modes:

Match domain regexp:

New From address:

New from name format: 

The mail list will rewrite the From: address based on list owners needs or preference.

Example - Setting Example DMARC Reject

This example uses  “DMARC policy suggests rejection” and will only be applied to domains who have the DMARC p=reject policy set on their mail servers.   This configuration requires the list owner to select the policy from the Protection modes list and click the update button.