How to Check IP & Domain Reputation
Reputation is invisible until it isn't. These free tools show how mailbox providers see your IPs and domains — so you can fix problems early.
TL;DR
Use Google Postmaster Tools, Microsoft SNDS and blacklist checks to monitor reputation. Watch trends, not single data points. If reputation drops, slow down and fix the root cause.
Google Postmaster Tools
Google Postmaster Tools shows your domain and IP reputation, spam rate, authentication results and delivery errors for Gmail — the single most useful free reputation source. Set it up first.
Microsoft SNDS
Microsoft SNDS gives data on how Outlook/Hotmail see your IPs, including complaint rates and trap hits.
Blacklist monitoring
Check your IPs and domains against major RBLs like Spamhaus, and use MXToolbox for a quick multi-list lookup. A listing routes you to spam — act fast (see blacklist removal).
What good looks like
- Postmaster domain/IP reputation: High or Medium.
- Spam rate: under 0.1%.
- Authentication: SPF/DKIM/DMARC passing.
- No active blacklist entries.
When reputation drops
Pause aggressive sending, identify the cause (bad list segment, content, a compromised account), fix it, then rebuild with engaged contacts — like a mini warmup.
AutoPMTA centralises reputation and blacklist monitoring so you see problems first. View plans.
Key takeaways
- Postmaster Tools is the best free Gmail reputation source.
- SNDS covers Outlook/Hotmail; check RBLs for blacklists.
- Watch trends and keep spam rate under 0.1%.
- On a drop: slow down, fix the cause, rebuild gradually.
Frequently asked questions
How do I check my sender reputation?+
Use Google Postmaster Tools for Gmail reputation, Microsoft SNDS for Outlook, and blacklist checkers like Spamhaus or MXToolbox. Together they show how providers view your IPs and domains.
What is a good IP reputation score?+
In Google Postmaster Tools, aim for 'High' or 'Medium' domain and IP reputation, a spam rate under 0.1%, and passing SPF/DKIM/DMARC authentication.
How often should I check email reputation?+
Monitor continuously if you send at volume — at minimum weekly. Catching a reputation dip or blacklist listing early limits the damage to your campaigns.