/ Glossary — Reputation & Bounces
What is sender reputation?
The trust score mailbox providers assign to your sending IP and domain, built from your sending history. It's the single biggest factor in whether your mail reaches the inbox. Here's what shapes it and how to protect it.
/ Definition
Sender reputation is the trust score that mailbox providers assign to your sending IP address and domain, based on how your mail has behaved over time. Providers like Gmail and Outlook track signals — how many recipients open or delete your mail, how often you're marked as spam, how clean your list is, whether you hit spam traps — and distil them into a reputation that decides whether your mail reaches the inbox, lands in spam, or is rejected outright.
It's the single most important factor in deliverability, and the one most within your control. Authentication proves your mail is really yours; reputation decides whether being really yours is a good thing. A sender with strong authentication but poor reputation still struggles, because the providers have learned that mail from this source isn't wanted.
/ In practice
IP reputation vs domain reputation
Reputation is tracked on two levels that work together. IP reputation attaches to the address you send from and governs the connection-level decision of whether to accept your mail at all — it's what a new IP has to earn through warming. Domain reputation attaches to the domain in your From address and increasingly carries more weight, because it follows you across IP changes. The practical consequence is that you can't fix a reputation problem just by switching IPs: a damaged domain reputation travels with you, while a clean one can partly support mail from a newer address.
How do you protect it?
Reputation is built slowly and lost quickly, so protection is mostly about consistency and hygiene. Send to engaged recipients who want your mail, suppress hard bounces and complaints immediately through a suppression list, keep volume steady rather than spiking, and never send to lists you didn't build with consent. Because reputation moves before you see its effects, watching the leading indicators through deliverability monitoring is what lets you correct a downward trend before it becomes a delivery problem.
/ Related terms
Reputation is earned slowly. We build it and guard it.
Warming, list hygiene, steady volume, and continuous monitoring are how a strong reputation is built and held — the operation we run so your mail keeps reaching the inbox. Bring us your sending and we'll protect the score.
Book infrastructure reviewRelated capabilities