Terms below appear throughout guides on email unsubscribe compliance. Each definition is one or two sentences; follow the links in the sidebar for the full guides.
Core terms#
Email unsubscribe compliance
Unsubscribe compliance covers the legal and provider requirements for letting recipients opt out: a visible link, one-click List-Unsubscribe headers (RFC 8058), and processing within a defined window.
SPF
A DNS record listing servers authorized to send for a domain. Checked against the connecting IP.
DKIM
A cryptographic signature on each message, verified with a public key in DNS.
DMARC
A policy record telling receivers what to do when SPF and DKIM fail alignment, plus reporting.
Alignment
Agreement between the visible From domain and the domain that passed SPF or DKIM.
Sender reputation
A provider's running assessment of a domain or IP based on complaints, bounces, engagement, and authentication.
Inbox placement
Share of accepted mail that lands in the inbox rather than spam.
Spam trap
An address that never opted in, used to catch senders with poor list practices.
BIMI
A DNS record pointing to a brand logo displayed next to authenticated mail; requires DMARC enforcement.
Feedback loop
A provider program that reports recipient spam complaints back to the sender.
Frequently asked questions#
What is one-click unsubscribe?
An RFC 8058 header pair that lets the mailbox provider send a POST to your endpoint when a user clicks Unsubscribe in the client, with no landing page.