What are signs your cold domain reputation is damaged?
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Your campaigns were fine last week. Now you're seeing weird patterns. Open rates dropped. Bounces crept up. Seeds you sent to your own test accounts landed in spam. What's happening? Domain reputation doesn't fail suddenly. It shows warning signs first, if you know where to look.
Deliverability signals. The easiest signs to spot are delivery rates that drop for no reason. If you've been hitting 95% delivery and suddenly you're at 88%, that's a flag. Watch bounce rates on addresses you know are valid. You shouldn't see bounces climbing when your list quality hasn't changed. Run seed tests (send to your own Gmail and Outlook accounts) and check where they land. If they're hitting spam on a domain that used to see inbox, you've got a problem.
Monitoring tools tell the story. Google Postmaster Tools shows your domain reputation in plain language: High, Medium, Low, or Bad. If it's dropped a level, investigate immediately. Microsoft SNDS reports are more technical but more valuable. Look for trap hits (you're mailing addresses that don't exist) or complaint spikes. Blocklist monitoring should show no new listings. If you spot one, that's urgent.
What recipients are telling you. Pay attention to reply patterns. You might notice more negative or hostile replies than usual. Unsubscribe requests might spike. If you're enrolled in feedback loops, check complaint data. And listen when recipients mention they found your email in spam. That's real data.
Technical signals matter too. SMTP error codes can reveal what ISPs are doing. More 4xx and 5xx errors (temporary and permanent rejections) mean ISPs are pushing back. You might see rate limiting messages telling you to slow down. These aren't random. They mean reputation pressure.
The critical move here is don't panic increase volume. The instinct to push through by sending more is backwards. Reduce volume, diagnose the root cause, fix it, then resume. A few hours of reduced sending beats weeks of damaged reputation.
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