Mailing list
An address that redistributes each message it receives to all its subscribers, changing the envelope sender so that bounces return to the list rather than to the author.
What it means
RFC 5321 distinguishes two ways one address can expand to many. An alias replaces the address and keeps the envelope sender; a list redistributes the message and changes the envelope sender to the list's administrator, so delivery errors reach someone who can fix the list, while the From header stays the author's. Lists usually add List- header fields, and many also tag the subject or append a footer; RFC 5321 says lists that modify messages extensively should be viewed as new senders posting a new message.
Those changes are what make lists hard on authentication. A changed subject or added footer breaks the author's DKIM signature, and the list's servers are not in the author's SPF record, so the author's DMARC can fail at the final receiver. RFC 7960 describes the mitigations lists use, such as rewriting From to the list's own address.
Related terms
Sources
What this definition rests on. The wording is ours; the facts are theirs.
- RFC 5321, section 3.9.2: Listrfc-editor.org
- RFC 7960, section 3.2.3: Mailing Listsrfc-editor.org
- RFC 7960, section 4.1.3.1: Changes to the RFC5322.Fromrfc-editor.org
All 432 terms in the glossaryThe wiki: blocklists and bounce codes