What does “domain reputation block” mean?
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You send a campaign, and the bounce message comes back referencing your domain. Not your IP. Your domain. That's a domain reputation block, and switching ESPs or warming up a new IP won't get you out of it.
A domain reputation block happens when an ISP rejects your mail because of the history tied to your sending domain (the domain in your From address). Mailbox providers like Gmail and Outlook have been tracking domain signals for years now, sometimes more closely than IP signals. Your domain follows you everywhere. Change your IP, change your ESP, it doesn't matter. The block travels with the domain.
A few things commonly damage domain reputation over time. Consistent spam complaints from recipients who don't remember signing up. Low engagement across your list. Spam trap hits from addresses that should never be mailed. DMARC failures caused by spoofing or misconfigured authentication. In the most serious cases, a domain associated with phishing will hit reputation floors that are nearly impossible to recover from.
The reason domain reputation has become so central is that it's much harder to fake than IP reputation. Anyone can spin up a new IP address. Domains take time to build trust, and that same persistence cuts both ways when something goes wrong.
If you're trying to confirm you're dealing with a domain reputation block, Google Postmaster Tools is one of the clearest places to check. It shows domain reputation signals directly for Gmail traffic. Your ESP's bounce logs will often include language referencing the domain specifically rather than the IP. That's your signal.
Recovery takes time (there's no quick fix here). The usual path is reducing send volume, pruning unengaged subscribers, fixing any authentication gaps, and rebuilding engagement slowly with your most active recipients. If the domain has been used in phishing, you may need to evaluate a fresh domain entirely.
Not sure where your domain reputation stands right now? Check if your domain is listed anywhere with our free Blocklist Checker, or drop into the SOS hotline if you're dealing with active blocks and need a second pair of eyes.
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