Sending reputation is per IP and per domain, and they are not the same
14 July 2026 · 5 min read
Receivers track both. The IP is who connected; the domain is who claimed to be sending. They accumulate separately and you need both.
What each responds to
- IP: volume, sudden changes, spam-trap hits, complaint rate.
- Domain: authentication, complaint rate, and how long it has existed.
Consequences people trip over
A shared IP means someone else’s behaviour affects yours. A brand new domain has no reputation at all, which is not neutral: it is suspicious, and it is why a first campaign from a fresh domain lands badly.
Warm up slowly, keep volume steady, and authenticate from day one so the reputation you build attaches to something.
More on deliverability
SPF, DKIM and DMARC in plain English
Three records, three different jobs, and one relationship between them that explains almost every "why is my mail in spam" question.
Why forwarded mail lands in spam
Forwarding breaks SPF every single time, by design. What keeps forwarded mail out of the spam folder is DKIM surviving the trip, and that is easy to break.
MTA-STS and TLS-RPT, and when they are worth it
SMTP encryption is opportunistic by default, which means it is trivially downgraded. These two records are the fix, and one of them is nearly free.