What is List-Unsubscribe Header?
A standard mail header advertising one-click unsubscribe, increasingly required by major mailbox providers for bulk senders. Honoring instant opt-outs preserves reputation better than hiding the exit.
Related terms
Transactional vs Marketing Email
Account messages users expect (receipts, resets, alerts) versus promotional campaigns needing consent and easy opt-out. Separating the streams protects critical delivery when marketing complaints spike.
Double Opt-In
Requiring new subscribers to confirm via an emailed link before joining the list. The extra tap filters typos and bots, producing smaller lists that engage better and complain less.
Complaint Feedback Loop
A mailbox-provider channel reporting when recipients mark mail as spam, so senders can suppress complainers immediately. Ignoring complaints burns sender reputation far faster than any single campaign gains.
Return-Path Alignment
Matching the envelope sender domain used for SPF with the visible From domain that recipients see. Aligned domains let inbox providers credit authentication to the brand instead of the sending platform.
Sender Identity
The verified domain or address a provider is permitted to send from, proven through DNS records. BYOB projects verify sending domains before campaigns so transactional mail leaves from a trusted name.
DNS Verification (TXT)
Proving domain ownership by publishing a provider-issued token as a DNS TXT record. BYOB custom-domain and sender setup both use this challenge before activating routing or sending.