Your sender reputation determines whether your emails reach the inbox or land in spam. Mailbox providers calculate reputation based on your sending behavior, and they provide tools to help you monitor it. This guide covers the essential tools and what their metrics mean.
Google Postmaster Tools
Google Postmaster Tools is essential for anyone sending to Gmail recipients. It provides detailed data about your domain and IP reputation at Gmail.
How to Access
- Go to postmaster.google.com
- Sign in with a Google account
- Add and verify your domain
- Wait 24-48 hours for data to appear
Key Metrics
- Domain Reputation: High, Medium, Low, or Bad rating based on domain-level signals
- IP Reputation: High, Medium, Low, or Bad rating for your sending IPs
- Spam Rate: Percentage of delivered mail marked as spam by recipients
- Authentication: SPF, DKIM, and DMARC pass rates
- Encryption: Percentage of mail using TLS
Volume Requirements
Google Postmaster Tools requires significant sending volume to display data. If you send fewer than several hundred messages daily to Gmail, you may not see complete metrics.
Sender Score
Sender Score by Validity (formerly Return Path) provides an overall reputation score for your sending IP addresses on a 0-100 scale.
How to Check
- Go to senderscore.org
- Enter your sending IP address
- View your score and contributing factors
Score Interpretation
- 90-100: Excellent reputation, reliable inbox placement
- 80-89: Good reputation, minor filtering possible
- 70-79: Fair reputation, some spam filtering
- Below 70: Poor reputation, significant deliverability issues
Microsoft SNDS
Smart Network Data Services (SNDS) provides reputation data for Outlook.com, Hotmail, and other Microsoft email properties.
How to Access
- Go to sendersupport.olc.protection.outlook.com/snds
- Sign in with a Microsoft account
- Request access for your IP ranges
- Monitor filtering rates and complaint data
Key Metrics
- Status: Green (good), Yellow (moderate filtering), Red (significant blocking)
- Filter Result: Percentage of mail filtered to spam
- Complaint Rate: Spam complaints from Microsoft users
Yahoo Sender Central
Yahoo provides Sender Central for monitoring your reputation at Yahoo Mail and AOL.
Access and Features
- Register at sendercentral.yahoo.com
- View delivery metrics and reputation status
- Access feedback loop data
- Submit remediation requests if blocked
Blocklist Monitoring
Check if your IP or domain appears on major blocklists using MXToolbox:
- Go to mxtoolbox.com/blacklists.aspx
- Enter your IP address or domain
- Review listings across 100+ blocklists
What to Monitor Regularly
- Daily: Spam complaint rates, bounce rates
- Weekly: Domain and IP reputation scores, authentication rates
- Monthly: Blocklist status, overall trends
Setting Up Alerts
Do not wait to discover reputation problems. Set up monitoring:
- Configure Google Postmaster Tools email alerts
- Use MXToolbox for blocklist monitoring alerts
- Monitor bounce rates in your sending platform
- Track spam complaint rates through feedback loops