Google Postmaster Tools

Google Postmaster Tools is a free Google service that shows senders how Gmail treats their mail, including spam rate, authentication results, encryption, delivery errors and compliance with Gmail's sender requirements. Senders verify a domain through DNS to see its data.

Deliverability & Email InfrastructureUpdated September 30, 2026

In short

Google Postmaster Tools is Gmail's official dashboard for spam rate, authentication and compliance.

Key points

  1. Access requires verifying domain ownership by adding a TXT or CNAME DNS Record, which usually takes effect within minutes [1].
  2. Google's help center lists dashboards for compliance status, spam rate, IP and domain reputation, Feedback Loop (FBL) data, authentication, encryption and delivery errors [2].
  3. The spam rate shown there is the figure Gmail uses for its 0.3 percent limit in the Bulk Sender Requirements [3].
  4. Spam rate counts only inbox-delivered mail that users reported, so heavy spam-folder placement can make it look low [2].
  5. Data can be missing on low-volume days to protect user privacy, which limits its use for very small senders [1][2].

What the dashboards show

Postmaster Tools gives senders a view of their traffic from Gmail's side. Google's documentation describes a Compliance status dashboard that grades a domain against the sender guidelines, a Spam rate dashboard, IP Reputation and Domain Reputation views, a Feedback loop dashboard for senders using the Feedback-ID header, and dashboards for Email Authentication results, TLS encryption and delivery errors [2]. The authentication view shows the share of traffic passing SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail) and DMARC. Delivery errors show rejection and deferral rates with reasons, which helps explain a rise in Soft Bounce or Hard Bounce results. Together they give the most direct available signal of how Gmail sees your Sender Reputation.

Setting it up

To start, a sender signs in at postmaster.google.com, adds a domain and proves ownership with a DNS record [1]. Google's setup guide notes that verification usually happens right away but can take up to 10 minutes to show [1]. You should add the domain used in the From address and in DKIM signatures, and any Secondary Sending Domain you send from. Google has moved users to a newer interface and deprecated the old one [1]. Teams that want the numbers in their own reporting can use the Postmaster Tools API, which returns statistics such as the share of mail users marked as spam and delivery errors [4]. Data appears only after Gmail sees enough daily traffic from the domain, so a mailbox sending a few dozen Cold Email messages a day may see gaps, while senders of hundreds or more usually get steady charts.

Using the data well

The most important number is spam rate. Gmail requires senders to stay below 0.3 percent and recommends staying below 0.1 percent [3], and Postmaster Tools is where that rate is measured. Check it daily during Email Warmup and after any change in targeting or volume. Treat it together with delivery errors: if errors rise while spam rate stays flat, Gmail may be filtering or throttling before users see your mail. The compliance view is a quick way to confirm Domain Alignment and unsubscribe setup after DNS changes. Because the tool only covers Gmail, pair it with other signals, such as reply rates, bounces and Microsoft's SNDS, to judge overall Inbox Placement.

Sources
  1. Set up Postmaster Tools — Gmail Help
  2. Postmaster Tools dashboards — Gmail Help
  3. Email sender guidelines — Gmail Help
  4. Postmaster Tools API overview — Google for Developers
External sources open in a new tab.

Related terms

Spam Complaint Rate

Spam complaint rate measures how often recipients hit the spam button, and it must stay well under 0.3 percent.

Domain Reputation

Domain reputation is the track record your domain name builds with mailbox providers, and it travels with you wherever you send from.

Bulk Sender Requirements

Large mailbox providers now require authentication, low complaints and easy unsubscribes from high-volume senders.

Email Authentication

Email authentication proves to receiving servers that your domain actually sent your mail, and it is now mandatory for reaching Gmail, Yahoo and Outlook at volume.

Feedback Loop (FBL)

A feedback loop tells senders who marked their mail as spam so those people can be removed.

Sender Reputation

Sender reputation is how much a mailbox provider trusts your mail, and it is earned or lost through how recipients react to what you send.

Mentioned in
Email DeliverabilityFollow-Up EmailInbox PlacementIP ReputationOpen RateSecondary Sending DomainSoft BounceSpam Trigger Words

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