Sender reputation
A mailbox provider's ongoing assessment of a sending domain, built from bounce rate, spam complaints, and engagement over time. Low reputation means spam-folding by default, regardless of content.
A mailbox provider's ongoing assessment of a sending domain, built from bounce rate, spam complaints, and engagement over time. Low reputation means spam-folding by default, regardless of content.
What it is made of
Mailbox providers do not publish a score, but the inputs are well understood:
- Complaints. Recipients marking you as spam. The heaviest signal. See complaint rate.
- Bounces and trap hits. Mail to dead addresses says your list is badly kept. See hard bounces and spam traps.
- Engagement. Whether mail is opened, replied to, or deleted unread.
- Authentication. SPF, DKIM and DMARC passing and aligned.
- Consistency. Sudden jumps in volume look like a compromised account.
Domain and IP are separate
Reputation attaches to the sending IP and to the domain in the From address and DKIM signature. Providers increasingly weight the domain, because an IP can be changed in an afternoon and a domain cannot. On a shared IP you inherit the pool's history; on your own domain you carry your own wherever you send from.
It moves slowly in both directions
A new domain starts with no history, which providers treat cautiously. That is why warming up exists. Damage is quicker than repair: a bad week can take weeks of clean sending to undo.
How to see yours
Google Postmaster Tools shows domain reputation and spam rate for Gmail traffic, if you send enough volume to populate it. For everything else, the leading indicators are bounce rate and the rate of replies versus silence. Check public blacklists when something looks wrong, and read what a high bounce rate costs.
Also see: Bounce rate, Domain warmup
Ready to try it on a real list?
A mailbox provider's ongoing assessment of a sending domain, built from bounce rate, spam complaints, and engagement over time. Low reputation means spam-folding by default, regardless of content.
Get startedRelated
- Bounce rate — cold email glossary
The share of sent emails a mail server refuses to deliver. A hard bounce means the mailbox does not exist; a soft bounce means it is temporarily unreachable.
- Domain warmup — cold email glossary
Gradually increasing send volume on a new or dormant domain so mailbox providers build trust in it, rather than throttling or spam-folding it by default.
- Cold email & deliverability glossary
Plain-language definitions for the terms that come up in cold outreach and email deliverability: bounce rate, catch-all, SPF/DKIM/DMARC, sender reputation, and more.
- Hard bounce — cold email glossary
A permanent delivery failure: the mailbox does not exist, the domain does not accept mail, or the server has rejected the recipient for good. Hard bounces are the ones that wreck sender reputation.