Monitoring Email Deliverability with Google Postmaster Tools

Postmaster Tools is a set of Google tools for analyzing and improving email deliverability in Gmail. The data helps you assess how Gmail and its users respond to your campaigns.

Google has updated Postmaster Tools with a new interface. The main dashboard is now Compliance status, which checks your domain against Gmail's sender requirements. Domain reputation and IP reputation remain available in the old version through Visit old Postmaster Tools. For regular monitoring, focus primarily on Compliance status, Spam, and Authentication.

The new version includes these dashboards:

• Compliance status
• Spam
• Feedback Loop
• Authentication
• Encryption
• Delivery Error

Setting Up Postmaster Tools

1. Go to Postmaster Tools.
2. Enter your domain and add the TXT record provided by Google to your DNS to verify domain ownership.

After the domain is verified, you can use the dashboards described below.

Compliance Status

Compliance status is the main dashboard in the new Postmaster Tools. It shows whether your primary domain meets Gmail's sender requirements. Data from subdomains is also used to evaluate compliance for the primary domain.

Each requirement has one of three statuses: Compliant, Needs work, or No data found.

The following requirements apply to all senders:

• SPF and DKIM authentication — your mail passes SPF and DKIM.
• DNS records — your sending domain has valid DNS records.
• Message formatting — messages meet Gmail's formatting requirements.
• Encryption — traffic is sent over TLS.
• User-reported spam rate — your spam rate stays within Gmail's limit.

For bulk senders, the dashboard also checks:

• DMARC authentication — your mail passes DMARC.
• One-click unsubscribe — bulk messages support one-click unsubscribe.
• Honor unsubscribe — unsubscribe requests are processed promptly.

During sending, aim to keep all applicable requirements Compliant. If a status changes to Needs work, pause volume increases and investigate the cause. No data found can mean that Google does not yet have enough qualifying email to evaluate the requirement.

Below the table, the Deliverability analysis section highlights specific issues — for example, a high rate of delivery errors — and provides a recommended action for each.

Spam

The Spam dashboard shows the percentage of DKIM-authenticated messages delivered to the Inbox of engaged Gmail users and then marked as spam by recipients. Messages that Gmail sends directly to Spam are not included in this user-reported spam rate.

The graph compares your user-reported spam rate with two reference lines shown in the Google interface: the recommended threshold (0.1%) and the policy violation line (0.3%). Keep your rate at or below the recommended threshold.

For eSputnik's thresholds and recommended actions for different spam-rate levels, see Deliverability Control Process.

Feedback Loop

The Feedback Loop dashboard shows the average spam rate for messages identified by Feedback Loop IDs and the number of unique identifiers per day.

According to the Google Feedback Loop specification, the Feedback-ID header can contain campaign identifiers and a required sender ID. eSputnik uses an identifier that combines the message type with the campaign or message ID, followed by the eSputnik sender ID.

• Feedback-ID for a broadcast: b4502231:eSputnik.com
• Feedback-ID for a trigger campaign: t197398:eSputnik.com
• Feedback-ID for a single message: im14413670895:eSputnik.com

The prefix before the number identifies the type: b is a broadcast, t is a trigger campaign, and im is a single message. The number identifies the corresponding broadcast, trigger campaign (sent through a workflow or the Smartsend method), or single message, such as a test or a message sent using v1/message/email.

To find which campaign caused complaints, open Feedback Loop, copy the identifier, for example, b5273156, and enter it under Campaigns → Reports → Email → Broadcasts/Triggered in the format cid:1234567.

Authentication

The Authentication dashboard shows the percentage of email that passes SPF, DKIM, and DMARC authentication. Separate SPF, DKIM, and DMARC success rates are shown for each day.

Encryption

The Encryption dashboard shows the percentage of inbound and outbound traffic encrypted with TLS (Transport Layer Security). The dashboard reports inbound TLS rate and outbound TLS rate.

Delivery Error

The Delivery Error dashboard shows the percentage of authenticated messages that Gmail rejected or temporarily failed to accept. The table below the graph groups the reasons by Error Type:

• Temp Fail — for example, Rate limit exceeded or Suspected spam. These are temporary SMTP 4.x.x errors; the system may retry delivery.
• Reject — for example, Bad or unsupported attachment or Email content is possibly spammy. These are permanent SMTP 5.x.x errors.

A sharp increase in delivery errors is often associated with a sudden increase in send volume or an infrastructure issue. Reduce the sending rate and review the reasons listed in the table.

Legacy: Domain and IP Reputation

Domain reputation and IP reputation are available in the old version of Postmaster Tools through Visit old Postmaster Tools.

Domain reputation reflects your domain's reputation in Gmail. If it drops, review the campaigns sent during the affected period. A low reputation increases the risk that messages will be delivered to spam.

IP reputation reflects the reputation of the sending IP address:

• High — the IP has a strong sending history and messages are rarely marked as spam by Gmail.
• Medium — most email has fair deliverability, but a noticeable increase in spam can affect delivery.
• Low — email from the IP is likely to be marked as spam.
• Bad — email from the IP is almost always marked as spam or rejected.