Email deliverability glossary: 40 terms every sender should know
Forty email deliverability terms defined in one or two sentences each: bounces, SPF, DKIM, DMARC, spam traps, greylisting, sender reputation, inbox placement and verification.
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Deliverability, explained.
Guides and research on email verification, bounce rates, catch-all domains, disposable addresses, list hygiene and sender reputation. Written by the people who run the engine.
14 posts tagged deliverability
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@Real-time email validation on sign-up forms: how it works and what it catches
Real-time email validation checks an address as it is typed: syntax, typos, disposable domains, role accounts, MX and an optional mailbox check. Here is how it works.
@Role-based email addresses: should you email info@ and sales@?
Role accounts like info@ and sales@ belong to a function, not a person. Why ESPs distrust them, the consent problem, when B2B senders can still use them and how to detect them.
@Sender reputation in 2026: what the Gmail and Yahoo bulk sender rules mean for you
Sender reputation explained: what Gmail and Yahoo measure, the February 2024 bulk sender rules one by one, how bounces and complaints feed it, and a 30-day recovery plan.
@How to reduce your email bounce rate (and why 2% is the line)
Keep hard bounces under 2% or mailbox providers start throttling you. Hard versus soft bounces, the main causes, a step by step cleanup plan and sunset policies.
@Catch-all domains explained: why 'accept all' makes verification hard
A catch-all domain accepts mail for every address, real or not, so a verifier cannot confirm a mailbox. Here is how we detect it and how to mail those contacts safely.
@Greylisting explained for marketers: why some mail is delayed
Greylisting is a mail server tactic that temporarily rejects unfamiliar senders with a 4xx code and accepts the retry. What it looks like in your reports, how long it lasts and what to do.
@The email list hygiene checklist for 2026
A ten-step email list hygiene checklist: verify at capture, clean before big sends, drop role and disposable addresses, sunset the unengaged and keep your bounce rate under 2%.
@Email verification for cold outreach and B2B prospecting
Cold lists are guessed, scraped and aged, so they bounce more. How to verify before every sequence, handle catch-all domains, stay under 1% bounces and keep the programme compliant.
@Email list decay: how fast do email lists go bad and what to do
Email lists typically lose 22% to 30% of their valid addresses every year. What drives decay, what it does to a 10,000-contact list, how to measure your own rate and how often to re-verify.
@What is a spam trap and how do you avoid sending to one?
Spam traps are addresses that exist only to catch senders with bad lists. The three types, how they end up on your list, what verification can and cannot detect, and how to stay clear.
@Hard bounce vs soft bounce: what the difference means for you
A hard bounce is a permanent rejection (5xx), a soft bounce is temporary (4xx). What causes each, how ESPs handle them, and when a soft bounce should be treated as hard.
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