Deliverability
What is Sender Reputation?
A mailbox provider's trust score for a sending IP and domain that drives inbox placement.
Sender reputation is the aggregate trust score mailbox providers assign to a sending identity, computed per IP and per domain from signals like complaint rates, bounce rates, spam-trap hits, authentication results, engagement, and sending consistency. A strong reputation lands mail in the inbox, while a poor one routes it to spam or gets it rejected. Providers keep their own internal scores, and tools such as Google Postmaster Tools expose a domain and IP reputation grade that builds and decays based on recent behavior.
Why it matters for cold email
Sender reputation is the single biggest lever in cold email deliverability, because every other practice (authentication, warming, list hygiene, and keeping bounces and complaints low) ultimately feeds into the score that decides whether prospects ever see your message.
Related terms
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