Glossary Archive

Email addresses created solely to identify unsolicited senders. They were never owned by a real user; hitting them often indicates scraping or poor data sources.

A DNS record used for reverse DNS (rDNS) that maps an IP address to a hostname; used as a trust signal in email.

Purchased list is a bought list of emails/phone numbers used for outreach without direct consent from recipients; high-risk for compliance and deliverability.

A policy action where messages are routed to spam/quarantine instead of inbox (e.g., via DMARC policy or security filtering).

A mailbox provider’s cap on how much mail it will accept from a sender over a period. Exceeding limits can cause temporary failures/deferrals (soft bounces).

Reverse DNS: checking that a sending IP maps via PTR to a hostname, often compared with forward DNS, used as a legitimacy signal.

Formerly valid user addresses that were abandoned and later repurposed as traps. Hitting them often indicates poor list hygiene and failure to remove long-inactive addresses.

Remediation is the process of resolving blocklisting or repairing reputation for a domain/IP (e.g., fixing root cause, requesting delisting, adjusting sending).

Mailbox providers’ trust rating for a sender’s domain and IP based on signals like complaints, bounces, traps, engagement, and consistency.

Return Path is the envelope-from/bounce address used to receive bounces and delivery reports. (Also historically a company name in deliverability.)