Glossary Archive

The ongoing process of maintaining a mailing list: removing hard bounces, unsubscribes, complainers, and long-term inactives; optionally updating addresses responsibly.

List maintenance is the regular review and actions to protect reputation: re-engage or suppress inactives, handle bounces/complaints, and keep acquisition sources clean.

An email header that enables mailbox clients to show an easy unsubscribe option (often one-click). Can be implemented via mailto and/or HTTPS methods.

A service that hosts mailboxes and filters incoming mail (e.g., Gmail, Outlook, Yahoo). Also called mailbox providers/ISPs in deliverability contexts.

Malware is malicious software intended to damage systems, steal data, or gain unauthorized access; often distributed via links or attachments.

Messaging compliance is adhering to applicable laws and platform policies for messaging (email/SMS), including consent, identification, and unsubscribe requirements.

In seed-list inbox testing, a result where the seed address did not receive the message in either inbox or spam—often due to blocking, rejection, or sending issues.

Mail Transfer Agent (MTA): server software that relays email between systems using SMTP.

Mail User Agent: software used by end users to read and send email (e.g., Outlook, Apple Mail, Gmail web).

MX is a DNS record type that routes inbound email for a domain to designated mail servers.