Google Postmaster Tools is a free Gmail dashboard that shows how Google rates the mail you send from your domain: your reputation tier, your user-reported spam rate, whether your messages pass SPF, DKIM and DMARC, and why Gmail delayed or rejected anything. You set it up by adding one TXT record to your domain's DNS to prove ownership, then you wait for volume to build before the graphs populate. It is the only place Gmail tells you, in its own words, what it thinks of you.
Reads public DNS only. Nothing is stored unless you save the domain to an account.
The catch that trips up most people: Postmaster will show almost nothing until you send authenticated mail at real volume to Gmail addresses, and authentication is exactly where domains fail silently. Confirm your SPF, DKIM and DMARC are correct first, then verify the domain, then read the dashboards below.
Why Postmaster Tools matters before you send
Gmail decides inbox versus spam per message, and a big input to that decision is how it has treated your domain historically. Postmaster is the feedback channel for that reputation. Without it you are guessing why campaigns land in spam. With it you can see, day by day, whether Gmail trusts your domain, how many recipients hit the spam button, and whether your authentication is holding.
It is not a monitoring tool you check once. Treat it as a gauge you glance at during and after every send, especially when you change infrastructure, add a new sending platform, or ramp volume. A reputation drop shows here days before your open rates crater.
One hard requirement to understand up front: Postmaster only reports on domains that send enough mail to Gmail to be statistically meaningful. Low-volume senders will see "Not enough data" on most panels. That is expected, not a bug.
Step 1: Verify your domain with a TXT record
Go to postmaster.google.com, sign in with any Google account, and click the plus button to add your domain. Enter the domain that appears in the From address of the mail you send, for example yourdomain.com, not a subdomain unless you send from one.
Google gives you a verification string. The durable, recommended method is a DNS TXT record at the root of the domain. It looks like this:
yourdomain.com. IN TXT "google-site-verification=Xa1bC2dE3fG4hI5jK6lM7nO8pQ9rS0tU"
Add that record at your DNS host exactly as Google provides it, keeping the google-site-verification= prefix. Do not wrap it in extra quotes beyond what your DNS panel adds automatically. If you already verified this domain for Search Console or Google Workspace using a TXT record, Postmaster usually recognizes it and marks you verified instantly.
DNS changes take time to propagate. Give it anywhere from a few minutes to a few hours, then click Verify. If it fails, check that you added the record to the correct zone and that you did not accidentally create it as a CNAME or on a www subdomain. A TXT lookup from your terminal with dig TXT yourdomain.com +short confirms the record is live before you retry.
If you send from several domains or subdomains, add each one separately. Reputation is tracked per domain, and a subdomain has its own reputation distinct from its parent.
Step 2: Confirm authentication so the data can appear
Verification proves you own the domain. It does not make data appear. Postmaster only attributes mail to your domain when that mail passes DKIM aligned to your domain, or in some cases SPF, so Google can reliably tie the message back to you. If your DKIM signature uses a shared platform domain instead of yours, Postmaster credits the platform, not you, and your dashboard stays empty.
This is the moment to check that your records are actually correct rather than assume they are. Run your domain through the free deliverability checker to confirm SPF resolves, DKIM is present and signing with your domain, and DMARC is published. If any of the three is broken, fix it before you expect Postmaster to report anything. Our checker confirms exactly the SPF, DKIM and DMARC that Postmaster requires before it will ever show data, and points at the specific record that is wrong.
Two common blockers:
DKIM alignment
Postmaster needs DKIM that aligns with your From domain. If your platform signs with d=platform-mail.com instead of d=yourdomain.com, set up domain-level DKIM in that platform. Our guides on SPF, DKIM and DMARC and meeting Google and Yahoo sender rules cover the exact records.
A published DMARC policy
Bulk senders to Gmail must publish DMARC. Even a monitoring-only policy satisfies the requirement and unlocks better data. A minimal starting record is v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com. If you have not published one, follow how to set up DMARC.
Step 3: Read the reputation dashboards
Once volume flows, Postmaster shows several graphs. Here is what each one means in practice.
Domain and IP reputation
Reputation is bucketed into four tiers: High, Medium, Low and Bad. High means Gmail rarely marks your mail as spam and you have a strong history. Medium is a solid domain that occasionally trips filters, usually recoverable by cleaning your list. Low means a fair number of your messages get filtered and you should treat it as a warning. Bad means Gmail actively distrusts you and most of your mail goes to spam or gets rejected. Domain reputation follows your From domain; IP reputation follows the sending IP, which matters more on dedicated IPs than on shared pools. If you want the distinction spelled out, read domain reputation versus IP reputation.
Spam rate
This is the single most important number. It is the percentage of your delivered mail that Gmail users marked as spam, measured against messages that reached the inbox. Google's own guidance is to keep this below 0.10 percent and never let it reach 0.30 percent. The graph is your early-warning system: a spike here precedes a reputation drop. If it climbs, stop sending to unengaged recipients, tighten your opt-in, and remove anyone who has not opened mail in months. The spam rate is user-driven, so the fix is always about who you send to and how wanted the mail is.
Authentication
Three lines show the share of your traffic passing SPF, DKIM and DMARC. In a healthy setup all three sit near 100 percent. A DKIM line well below 100 usually means a second sending source is not signing correctly, or a selector is misconfigured. A DMARC line that lags SPF and DKIM points at an alignment problem. Anything under 100 here is a concrete task, not noise.
Delivery errors
This panel breaks down the percentage of your mail that Gmail temporarily or permanently rejected, and why: reputation, rate limiting, content or policy. Rate-limiting errors mean you ramped volume too fast and should slow down. Reputation errors track your Bad or Low standing. This is where a failing send explains itself.
Feedback loop (FBL)
The FBL is for high-volume senders who tag their mail with an identifier. When Gmail users mark tagged mail as spam, Postmaster reports the spam rate per identifier so you can trace complaints back to a specific campaign, template or stream. Most senders will not see FBL data until they implement the identifier header and reach the volume threshold, but it is the sharpest tool for pinning down which mail stream is generating complaints.
Step 4: Act on what you see
Postmaster tells you what is wrong; it does not fix anything. A practical response loop:
- Spam rate rising: cut unengaged recipients and audit your opt-in.
- Authentication below 100 percent: find the unsigned or misaligned source and correct DKIM or SPF.
- Reputation slipping to Low or Bad: reduce volume, send only to your most engaged recipients, and rebuild slowly. Our guide on why emails go to spam covers the recovery playbook.
- Delivery errors from rate limiting: pace your sends and warm up gradually.
Postmaster data lags by a day or two, so change one thing at a time and watch the trend rather than a single day.
Frequently asked questions
How long until Google Postmaster Tools shows data?
Verification is near-instant once your TXT record propagates, but the dashboards need volume. You typically need to send hundreds of messages a day to Gmail addresses, consistently, before reputation and spam-rate graphs populate. Low-volume senders may only ever see "Not enough data."
Why is my Postmaster dashboard empty even though I send lots of mail?
Almost always an authentication or alignment problem. If your mail does not pass DKIM aligned to your From domain, Google cannot attribute it to you, so nothing appears. Confirm your DKIM signs with d=yourdomain.com and that DMARC is published, then wait for the next data cycle.
Do I need to verify subdomains separately?
Yes. Reputation is tracked per domain, and a subdomain like mail.yourdomain.com has its own reputation and its own Postmaster entry. Add and verify each sending domain and subdomain individually.
What spam rate is safe in Postmaster Tools?
Keep it under 0.10 percent. Gmail treats 0.30 percent as the danger threshold, and sustained rates near or above it push your domain toward Low or Bad reputation. Below 0.10 percent is the target for a healthy sender.