Why It Matters
ISPs have shifted from IP-based reputation to domain-based reputation as the primary signal. That means changing IPs or email providers won't save you if your domain has a bad reputation — the problems follow you. Google Postmaster Tools shows domain reputation on a four-level scale: High, Medium, Low, and Bad. Once you drop to "Low" or "Bad," inbox placement craters and recovery takes weeks of careful sending.
How It Works
Every time you send an email, the receiving ISP logs how it performs against your domain. Opens, clicks, and replies are positive signals. Bounces, complaints, and spam trap hits are negative. Over thousands of data points, the ISP builds a reputation profile for your domain. This profile determines whether your next email goes to the inbox, spam, or gets rejected.
Domain reputation is separate from IP reputation, and you need both to be healthy. But domain reputation is stickier — it persists even when you change your sending infrastructure.
Quick Tips
- Check Google Postmaster Tools weekly. It's the only place to see how Gmail rates your domain reputation directly.
- If reputation drops, reduce volume and send only to your most engaged subscribers. You need positive engagement signals to rebuild trust.
- Use separate subdomains for marketing vs. transactional email. A marketing reputation problem shouldn't affect your password reset emails.
- New domains start with no reputation, which ISPs treat cautiously. Warm them up gradually just like you would a new IP.