Google Postmaster Tools

Postmaster Tools turns Gmail’s otherwise invisible filtering signals into dashboards you can read. Once a domain is verified, Google surfaces the data it has on mail you send to Gmail addresses, organised into several panels. The most important is your spam rate (the share of your delivered mail that recipients reported as spam), now paired with a compliance status panel that checks your mail against Gmail’s bulk-sender requirements.

Alongside those, it reports authentication pass rates for SPF, DKIM, and DMARC; an encryption panel showing the share of mail carried over TLS; a delivery errors panel breaking down rejected and temporarily failed mail; a feedback loop panel for campaign-level complaint data; and a compliance status panel that checks your mail against Gmail’s bulk-sender requirements. It does not show you per-recipient detail or anything about non-Gmail mail; it is a Gmail-only mirror.

• Spam rate. The percentage of your delivered, DKIM-authenticated Gmail mail that users marked as spam. The single most actionable number in the tool.
• Domain and IP reputation (retired). Gmail used to grade these on a four-band scale, but Google removed both dashboards on 30 September 2025.
• Authentication. The share of your traffic passing SPF, DKIM, and DMARC, a quick way to spot a misconfigured sending source.
• Encryption. The percentage of inbound and outbound mail sent over TLS.
• Delivery errors. The proportion of mail rejected or deferred, with the specific reasons.
• Feedback loop. Per-campaign spam rates for senders who embed an FBL identifier header.
• Compliance status. Whether your mail meets the bulk-sender rules (authentication, one-click unsubscribe, spam rate, and more).

For years, the panels senders fixated on were the domain and IP reputation grades. Google rated both on a four-band scale, and the meanings are worth knowing because the language still appears everywhere:

• High: a history of very low spam rates that complies with Gmail’s sender guidelines. Mail is trusted.
• Medium: mostly legitimate mail that occasionally sends spam. Usually still delivered, but watch the trend.
• Low: a history of sending a significant volume of spam. Expect filtering to the spam folder.
• Bad: a history of sending a high volume of spam regularly. Mail is routinely rejected or spam-foldered.

Google retired those reputation dashboards on 30 September 2025, when the legacy interface closed, on the grounds that a single static grade no longer reflects how its filters decide placement. The grade is gone, but the concept is not: today you read your Gmail standing from the spam-rate dashboard, the compliance status panel, and your real inbox placement instead of a one-word band.

You verify ownership of each sending domain by adding a DNS TXT record (or reusing an existing Google Search Console verification). The data is keyed to the domain in your DKIM signature and the visible From:, so verify the domain you actually authenticate and send from.

Postmaster Tools is authoritative, but only about Gmail. It says nothing about how Outlook, Yahoo, or Apple Mail see you, so it is one input, not a complete reputation picture. It also has a volume floor: panels stay empty until you send a meaningful daily volume to Gmail, which is why low-volume and brand-new senders often find it blank. And the data is aggregate and slightly delayed, so it is a monitoring tool for trends rather than a real-time alarm. Pair it with your own metrics and a broader reputation check across providers.