Sender reputation is the score mailbox providers assign to a sending domain and IP based on complaint rates, bounce rates, engagement, spam-trap hits, and authentication history. It determines whether mail is delivered, filtered, or rejected.
What good looks like#
- Done: Register in Google Postmaster Tools and Microsoft SNDS to see your domain and IP reputation directly.
- Done: Keep spam complaints below 0.1% (Gmail's threshold is 0.3% for enforcement) and hard bounces below 2%.
- Done: Segment by engagement and stop sending to contacts inactive for 90+ days.
- Done: Authenticate with SPF, DKIM, and DMARC so reputation accrues to your domain rather than a shared IP.
- Done: Ramp volume gradually after any pause longer than two weeks.
What bad looks like#
- Seen in audits: Buying or scraping lists, which seed spam traps into your database.
- Seen in audits: Blasting an entire list after months of silence.
- Seen in audits: Ignoring Postmaster Tools until placement has already collapsed.
How to move from bad to good#
Work through the good list in order and re-verify after each change. Most teams find one or two items from the bad list already present; fixing those usually produces the largest improvement.
Frequently asked questions#
Domain reputation vs IP reputation: which matters more?
Domain reputation now dominates at Gmail and Yahoo. IP still matters for Microsoft and for dedicated-IP senders.
How long does it take to repair a bad reputation?
Four to eight weeks of clean, low-volume sending to engaged recipients is typical.