Unsubscribe
The mechanism by which a recipient opts out of receiving future email — legally required to be clear and prompt.
Unsubscribe is the mechanism by which a recipient opts out of receiving future marketing email from a sender. CAN-SPAM, GDPR, CASL, and most other email regulations require a clear and prompt unsubscribe mechanism. Failures here generate the highest legal exposure of any email-marketing operation.
The modern unsubscribe stack includes (1) a clear, visible unsubscribe link in every marketing email (typically in the footer); (2) one-click unsubscribe per RFC 8058 (List-Unsubscribe header) so that Gmail and similar clients can offer a native unsubscribe button; and (3) prompt processing — CAN-SPAM allows up to 10 business days, but most senders process within hours or minutes.
A few patterns to avoid: requiring the user to log in to unsubscribe, requiring multiple confirmations, defaulting opt-out forms to keep-most-categories, or dark patterns that disguise the unsubscribe link. These tactics generate spam complaints (which damage reputation far more than the unsubscribe itself would have) and increasingly trigger regulatory penalties.