Postmaster Tools by Gmail: A Revolution in Deliverability Monitoring

In March 2024, Google launched Version 2 of its Google Postmaster Tools dashboard, its tool which allows you to monitor the performance of your domains. On this occasion, the tool was subtly renamed Postmaster Tools by Gmail!

In recent months, this new tool has not failed to add new features, the ideal opportunity to take a quick overview.

PMT

Compliance Status: a key indicator of compliance

One of the most significant additions to Postmaster Tools by Gmail is the Compliance Status page, which allows senders to ensure their practices comply with Gmail's new requirements for email senders.

This dashboard evaluates several points such as Authentication (SPF, DKIM and alignment), Encryption, Spam Rate, One-Click Unsubscribe and very soon, the Honor Unsubscribe.

But have you noticed some subtle new features?

  • Gmail does not make a distinction between marketing emails and transactional emails... A domain used exclusively for transactional emails (order confirmation, invoice, etc.) can perfectly be considered as non-compliant with One-Click Unsubscribe, due to too many complaints for example… You will therefore have to comply.
  • The evaluation of One-Click Unsubscribe takes into account the List-Unsubscribe header, supplemented by the List-Unsubscribe-Post header, but also the Feedback-ID header.
  • In addition to the evaluation of the organisational domain, Gmail has just introduced a particularly important new mention: for a subdomain to be considered compliant, the organisational domain must also be compliant.
Compliance status

A more precise Feedback Loop

Google Postmaster Tools V2 improves visibility on complaints received from Gmail users via the Feedback-ID: there are more Identifiers shown than in the previous version...

Important clarification, if an identifier is present in this dashboard, even with a 0% complaint rate, it means that this message/campaign is problematic and action must be taken.

Double DKIM: a new standard for ESPs

With this update, Gmail is also encouraging the use of double DKIM signing for ESPs. In fact, ESPs that set up a second DKIM signature for sending to Gmail and also sign the Feedback-ID header are now able to see the identifiers of their clients' campaigns that have generated complaints.

To help you out, below is an overview of how to set up this second DKIM signature with your MTA:

PowerMTA

Into the configuration file

domain-key selector, yourdomain.tld, /etc/pmta/yourkeyfile
<domain *>
  dkim-headers Feedback-ID
  second-dkim-headers Feedback-ID
  second-dkim-sign  yes
  second-dkim-identity @yourdomain.tld
</domain>
GreenArrow

Into the messages Headers or the Custom Headers section of a MailClass

X-GreenArrow-DKIM: [{"from_domain":true,"allow_duplicate":true,"use_key_from":"yourdomain.tld/selector","selector":"selector"},{"domain":"yourdomain.tld","selector":"selector","allow_duplicate":true}]
KumoMTA

File: /opt/kumomta/etc/policy/dkim_data.toml

additional_signatures = ["YourSecondSignature"]
headers = [
…, “Feedback-ID”
]
[signature."YourSecondSignature"]
policy = 'Always'
domain = 'yourdomain.tld'
selector = 'selector'
Postfix

DKIM signature generated by OpenDKIM

File: /etc/opendkim/SigningTable (last line of the file)

* selector._domainkey.yourdomain.tld

File: /etc/opendkim.conf

MultipleSignatures yes
SignHeaders …, Feedback-ID

Only data present in Postmaster Tools by Gmail has value

You may have noticed, but the data present is not identical between Google Postmaster Tools and Postmaster Tools by Gmail.Gmail has indeed taken advantage of this new version to review some of these calculations, such as the complaint rate. Consequently, a domain which would have a complaint rate close to 1% in the old interface can perfectly comply with the 0.3% threshold of the new interface, and vice versa.

We must therefore only trust the data present in this new version of Google Postmaster Tools... Unless the data is not yet present there, such as for the reputations of domains and IPs.

Still no alert… But a solution exists!

Despite these numerous improvements, Postmaster Tools by Gmail still does not offer an alert system in the event of a problem with the reputation of a domain or IP. This means that you must consult the interface very regularly to detect possible anomalies.

Fortunately, the Reputation Monitor module in the Postmastery console allows you to continuously monitor reputation and receive alerts whenever a reputation change is detected. Thanks to this solution, you can react proactively and prevent deliverability problems from worsening without you realizing it.

What's next?

In the coming weeks and months, Gmail will gradually implement several new features:

  • Evaluation of the unsubscription processing on the Compliance Status. (This feature was briefly made available online on January 9, 2025, before being withdrawn.)
Honor Unsubscribe
  • A new dashboard on domain reputation
  • A new dashboard on IPs reputation
  • A new API (currently, the API only includes data from the V1)

These are just the new features we’re aware of, so, much like the evaluation of the organizational domain, it wouldn’t be surprising if other new features were introduced. As always with Google, we’ll need to closely monitor the interface!

Need help?

Having deliverability issues to Gmail? Do you need to monitor the reputation of your IPs and domains? Are you unable to set up a double DKIM signature? Postmastery provides a full range of services to address these requirements. If you have any needs, feel free to reach out to us!

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