What is Google Postmaster Tools?

Gmail does not send individual complaint reports to senders, so a Gmail-heavy list can look healthy in your SES complaint numbers while Gmail users are marking you as spam. Postmaster Tools is how you see that side. Its feedback loop gives large senders campaign-level data, identified by a Feedback-ID header you add to your mail.

What it shows

• Compliance status. Whether you meet Gmail’s sender requirements.
• Spam rate. The share of your messages that recipients manually mark as spam in Gmail.
• IP reputation and domain reputation. A quality rating for the IP addresses and domains you send from.
• Feedback loop. Campaign messages that recipients marked as spam, for large senders.
• Authentication. How much of your mail passed SPF, DKIM and DMARC.
• Encryption. Whether your mail was delivered over TLS.
• Delivery errors. Authenticated messages that were rejected or temporarily failed.

Getting started

1. Sign in with a Google account and add your sending domain.
2. Verify it by adding a TXT record to DNS.
3. Wait a day or two for data, if your volume is high enough to show any.

Add every domain you send from, including subdomains used for different streams of mail.

Limits

It reports only on Gmail traffic. It needs a minimum volume before it displays anything. And its figures are summaries, so it tells you something is wrong without telling you which message or recipient caused it.

Using it with Amazon SES

Check it when your SES numbers look fine but mail seems to be missing, and when you change your sending volume or content. A rising Gmail spam rate while your SES complaint rate stays flat is the typical sign that complaints are going unreported. Pair it with authentication checks, since failures there show up in both places.