Glossary Archive

A do-not-send list containing addresses that must be excluded (unsubscribes, hard bounces, complainers, legal suppressions, etc.).

Regulating send speed/volume to a provider to avoid deferrals or bounces. Throttling may be applied by the sender or enforced by the receiver.

Transport Layer Security: encryption used to secure connections between mail servers and clients; improves privacy and integrity in transit.

Non-marketing operational messages triggered by user/account actions (e.g., receipts, password resets). Typically sent regardless of marketing preferences, but still must follow applicable laws/policies.

A DNS record type that stores text-based values; commonly used for SPF, domain verification, and other authentication/validation records.

A trap address created from misspelled domains (e.g., @gmial.com). Hits indicate data-entry errors or poor list acquisition/validation.

A click metric counting each recipient once per link/campaign, even if they click multiple times.

Messages sent without the recipient’s consent; increases complaint/trap risk and often violates laws/platform policies.

An action a recipient takes to opt out of future mail. Unsubscribe requests must be honored promptly.

Unique unsubscribes ÷ delivered/received messages (definition varies); a key indicator of relevance and list quality.