Using Mailman? External Recipients May See a Change in the “From” Address

Starting April 25, 2024, when you send an email using Mailman mailing list software, those who get your message may notice a modification in the "From" address — if they use an external email service provider, like Google or Yahoo.

For these recipients, the "From" address could show a list-specific address, such as <@lists.stanford.edu>, instead of the sender’s email address.

• No impact to stanford.edu. Emails sent from a stanford.edu address or to recipients using a stanford.edu address will not be impacted.
• No change for senders. Your experience as a sender will stay the same, and you can continue using Mailman mailing list tools as usual.

Zoom in: Before and after the change

Today, when you send an email to a mailing list via Mailman, the recipient sees your email address in the "From" field:

From: Jane Stanford <jstanford@gmail.com>

After the change, the recipient may see a list-based address in the "From" field:

From: Jane Stanford via group-list <group-list@lists.stanford.edu>
Reply-To: Jane Stanford <jstanford@gmail.com>

Why is this change being made?

We’re implementing a technology update so emails will be delivered to all recipients on the Mailman mailing list without being flagged as “spoofing.” Spoofing is a technique used to forge the "From" address of an email message so it appears to come from a known sender.

With the rise of fraudulent emails and phishing scams, mailbox service providers are introducing more stringent sender authentication policies to prevent spoofing. However, in some cases, these new requirements can interfere with the delivery of legitimate inbound emails.

Dive in a little deeper

Currently, we’re only applying this change to domains with a strict DMARC (Domain-based Message Authentication, Reporting, and Conformance) policy. DMARC is an authentication protocol that lets email service providers verify an email was sent from a valid address so it can be accepted without being quarantined.

By making the change, we aim to proactively prevent emails sent through Mailman to domains outside of stanford.edu from getting rejected. This will also mitigate the risk of list owners facing automatic unsubscriptions of list members due to high bounce rates.