In the past, email deliverability was almost entirely about IP reputation. If your server's IP was "clean," you were good. Today, the landscape has shifted significantly towards Domain Reputation.
IP Reputation
This is the reputation of the physical server sending the email. It is tied to a specific number (e.g., 192.0.2.1).
- Pros: Easy to measure; heavily used by traditional blacklists (RBLs).
- Cons: Can be reset by changing IPs; shared IPs (like on SendGrid or Mailchimp) mean your reputation is affected by others.
Domain Reputation
This is the reputation of your brand's domain name (e.g., example.com). It follows you no matter which Email Service Provider (ESP) or IP address you use.
- Pros: Portable; you own it completely.
- Cons: Harder to repair if damaged; takes longer to build.
The Shift to Domain Reputation
Modern filters like Gmail's AI rely heavily on domain reputation. They track how users interact with emails from your domain:
- Do they open and reply? (Positive signal)
- Do they delete without opening? (Negative signal)
- Do they mark as spam? (Very negative signal)
How to Build Strong Reputation
1. Authenticate: Ensure SPF, DKIM, and DMARC are perfect.
2. Engage: Send content your users actually want. Remove inactive subscribers.
3. Consistency: Send regular volumes. Don't disappear for months and then blast 1 million emails.
4. Subdomains: Consider using separate subdomains for different types of mail (e.g., marketing.example.com vs receipts.example.com).