Cold email glossary
Domain reputation
Domain reputation is the trust assessment a mailbox provider assigns to a sending domain based on its history of authentication, spam complaints, bounces, spam trap hits, and recipient engagement. It is a major input into whether mail from that domain reaches the inbox, lands in spam, or is rejected.
What is domain reputation?
Every major mailbox provider keeps its own internal score for the domains that send it mail. The score is built from the domain's track record: how often recipients mark its mail as spam, how often addresses bounce, whether it hits spam traps, whether people open and reply, whether its volume is steady or spiky, and whether its SPF, DKIM, and DMARC records check out. Authentication is what ties mail to the domain in the first place, which is why a consistent DKIM signature matters for accumulating history at all.
Domain reputation is distinct from IP reputation, and over time it has become the heavier of the two. IPs are often shared or rotated, especially on large email platforms, so providers lean on the domain as the durable identity of the sender. The practical consequence: you cannot escape a damaged domain reputation by switching sending tools or IPs, because the reputation travels with the domain.
The dynamics are asymmetric. Reputation builds slowly, through weeks of consistent, authenticated sending that real recipients engage with, and it can drop in days after a complaint spike or a send to a dirty list. A brand-new domain has no reputation at all, which providers treat with caution, and that is the reason warmup exists: practitioners typically ramp a new domain gradually over several weeks rather than starting at full volume. Subdomains carry their own reputation, but providers can and do associate them with the organizational domain above them.
There is no single public score. The closest direct view is Google Postmaster Tools, which shows Gmail's assessment of a verified domain in four tiers (High, Medium, Low, and Bad) along with spam complaint data. Beyond that, senders infer reputation from proxies: bounce rates, spam complaint trends, blocklist appearances, and where seed-list tests land.
Why it matters in cold email
In cold email, domain reputation is the asset everything else depends on. The same list and the same copy perform completely differently sent from a trusted domain versus a damaged one, and recovery is slow enough that a burned domain is often retired rather than rehabilitated. It is also why cold outreach belongs on dedicated sending domains rather than the domain your company operates on: reputation cannot be reset, only rebuilt, and rebuilding is far cheaper on a domain whose only job is outreach.
How Sendful handles it
Sendful treats domain reputation as the thing being managed, not a side effect: each client's outreach runs on dedicated sending domains that are warmed before they carry campaign volume, kept entirely separate from the primary domain, and slowed the moment bounce or complaint signals start to dip. Onboarding is limited each month for the same reason, so no client's domains are pushed harder than their reputation can support.
How do I check my domain reputation?
Start with Google Postmaster Tools, which is free and shows Gmail's view of a verified domain in four tiers from High to Bad, plus spam complaint rates. There is no equivalent universal score across providers, so supplement it with blocklist checks and by watching your own bounce rates, complaint rates, and reply trends for early warning.
How long does it take to fix a bad domain reputation?
Typically weeks at minimum, and only if the cause is fixed first: stop the offending sends, clean the list, verify authentication, then rebuild with low volume to engaged recipients. If the domain is on major blocklists or rated Bad in Postmaster Tools, practitioners often find it faster to retire it and warm a fresh dedicated domain instead.
Does a new domain have a bad reputation?
Not bad, but unknown, and providers treat unknown senders cautiously. A domain registered last week that jumps straight to full campaign volume matches the opening move of a spam operation, so providers throttle or filter it. The fix is warmup: weeks of gradually increasing, authenticated sending that builds a positive history before real campaign volume begins.
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