Glossary Archive

A DNS record that specifies which mail servers receive email for a domain.

Non-human interactions are automated opens/clicks triggered by security and privacy systems (e.g., link scanners, MPP), which can inflate engagement metrics.

Open pixel is a tiny tracking image used to infer opens when downloaded; accuracy is limited due to image blocking and proxy prefetching (e.g., Apple MPP).

Open Rate is the percentage of emails that were opened (tracked) out of sent/delivered. Open tracking can be inaccurate due to image blocking and Apple MPP proxy opens. Open tracking can be inflated by Apple MPP and security scanning; use clicks/conversions as stronger engagement signals when possible.

Opt-In is a permission-based model where recipients explicitly agree to receive email marketing messages (e.g., checking a box, confirming signup).

Consent models: single opt-in adds a subscriber after one action; double opt-in requires a follow-up confirmation step (typically link click).

A model where messages are sent until a recipient unsubscribes. It is higher-risk for compliance and complaints than opt-in, and generally discouraged for marketing.

A recipient action to withdraw consent and stop receiving future messages from a sender.

Permission policy is the sending platform’s rules requiring proof of consent and acceptable acquisition practices for the traffic sent through their systems.

Fraudulent messages impersonating legitimate organizations to trick recipients into revealing sensitive information or installing malware.