Mailman is one of the most popular open source mailing list applications. 


By default, Mailman will attempt to send emails to members of lists by spoofing the From domain of the email sent to the list. Since this can cause problems when the From domain of the email being sent to the list is at DMARC enforcement, Mailman allows for configuration to address this.


There are two main ways that Mailman can address this issue. The first is by 'munging' the message where the From address of the email is changed to that of the mailing list. The second is to wrap the incoming message in an email from the mailing list. The configuration for these is covered in the Mailman docs here:


https://mailman.readthedocs.io/en/latest/src/mailman/handlers/docs/dmarc-mitigations.html