Glossary

What is sender reputation?

Sender reputation is the judgement a receiving provider forms about a sending IP and domain, from how recipients react to mail and how many addresses turn out not to exist. It decides whether mail reaches the inbox.

Also known as Sending reputation · IP reputation · Domain reputation

It is two reputations, not one

IP reputation attaches to the address the mail came from. It is what matters most on a dedicated IP, and least on a large shared one where your traffic is a rounding error next to everyone else’s.

Domain reputation attaches to the domain in your From address and the domains you authenticate with. It follows you between providers, which cuts both ways: moving ESP does not reset it, and a domain you have sent well from for years is an asset you should not spend on a cold list.

Both are formed by the receiving provider, privately, and neither is published as a number you can read. Google Postmaster Tools shows you a view of your own; nobody shows you a competitor’s, and any product that claims to is showing you a proxy.

What actually moves it

Complaints, most of all. Google’s sender guidelines ask senders to "keep spam rates reported in Postmaster Tools below 0.10% and avoid ever reaching a spam rate of 0.30% or higher" — the only threshold in this area with a published number behind it. Checked 2026-09-11.

Invalid addresses. A send with a high hard-bounce rate is read as evidence about how the list was built, because that is what it is. This is the one lever verification pulls directly.

Authentication. SPF, DKIM and a DMARC policy are table stakes for a bulk sender now, on both Google’s and Yahoo’s published requirements. The SPF and DMARC checker reads what a domain currently publishes.

Volume and consistency. A sudden jump in volume from an IP with no history is indistinguishable from a compromised account. Ramping is not superstition; it is how a receiving provider is given enough data to form a favourable judgement before it has to make a defensive one.

How VerifyInbox handles it

Reputation is also our own operational problem, which is why this page is not abstract. Every verification probe is metered against a specific sending IP carrying its own warmup day, pacing curve, per-provider sub-caps, reputation score and cooldown, with circuit breakers that reschedule rather than answer wrongly, and separate RBL and PTR monitoring. When there is no warmed capacity available a request gets a 503 with a Retry-After and no charge — a delayed answer being better than a wrong one. That machinery is invisible in the output and it is what decides whether the output is any good.

Repairing it

Stop sending to the segment that caused the damage, first. Continuing to send while trying to recover is the most common mistake and it extends the recovery rather than shortening it.

Then: verify and clean the list, fix authentication, reduce volume and rebuild it gradually, and send to your most engaged recipients for a while so the signal the provider sees is a good one. Reputation is built over weeks and damaged in one send, and that asymmetry is the whole reason to care about it before a campaign rather than after.

What we do not do

VerifyInbox does not test inbox placement, does not monitor blacklists on your behalf, and does not send campaigns. Those are three different products and we are not any of them. What this product does is remove the addresses that do not exist before they cost you the reputation — which is one lever, and a large one.

Check a domain’s sending authentication records and spot the common mistakes. No account, and it runs now: SPF & DMARC checker

Related terms

Sources

Primary sources checked 11 September 2026. If something here is out of date, tell us and we will correct it.

Sender reputation: questions

What is an email sending reputation and how can you improve it?

It is the judgement a receiving provider forms about your sending IP and domain from complaints, invalid addresses, authentication and volume patterns. Improve it by verifying lists before sending, suppressing hard bounces permanently, authenticating with SPF and DKIM under a DMARC policy, and ramping volume rather than jumping.

How does email sender reputation affect email deliverability?

It decides what happens to mail the provider has already accepted: inbox, spam folder, or throttled at the door. A poor reputation does not usually produce a bounce you can see — it produces silence, which is why it is often discovered late.

What are the Gmail and Yahoo sender requirement updates and what changed?

Both published requirements for bulk senders covering authentication with SPF and DKIM, a DMARC policy on the sending domain, one-click unsubscribe, and keeping spam complaint rates low. Read each provider directly — Google publishes its sender guidelines and Yahoo its Sender Hub best practices, and both are updated.

How many emails a day triggers the bulk sender requirements?

Google states: "If you send more than 5,000 messages per day to Gmail accounts, follow the Requirements for sending 5,000 or more messages per day." It is a volume trigger counted against Gmail accounts specifically, not your total send. Checked 2026-09-11.

How do you keep your emails out of spam and in the inbox?

Authenticate properly, send only to people who asked, make unsubscribing easy, keep complaint rates low, and remove addresses that do not exist before sending. No verifier can tell you where a message landed — that requires seed testing, which is a different product, and we do not offer it.