What are Postmaster Tools?
Google Postmaster Tools is a free service from Google that shows how Gmail treats your email. It's the closest thing to seeing inside Gmail's filtering decisions.
What it shows:
Domain reputation: High, Medium, Low, or Bad. This directly affects inbox placement at Gmail.
- IP reputation: The same scale for your sending IPs.
- Spam rate: Percentage of emails marked as spam by recipients. Critical metric.
- Authentication results: SPF, DKIM, and DMARC pass rates.
- Encryption: TLS usage for your email connections.
- Delivery errors: Why Gmail rejected messages.
How to set it up:
Verify domain ownership (DNS TXT record)
Wait for data to populate (requires sufficient volume)
Check regularly for changes
Limitations:
Only shows Gmail data (not Outlook, Yahoo, etc.)
Requires minimum volume for data to appear
Some metrics lag by a day or more
Doesn't show individual email details
If Gmail were a major shipping port, Postmaster Tools would be the harbor master's log book. It won't tell you everything, but it reveals whether your vessels are welcome or watched.
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