Understanding Google Postmaster for sender reputation monitoring

Overview

Google Postmaster Tools (GPMT) provide multiple insightful windows into the generally opaque calculation of sender reputations. When you monitor your GPMT dashboards regularly, you can get ahead of deliverability challenges.

While GPMT only reports data from Gmail users' interaction with your email marketing program, Gmail has, by far, the largest market share of any inbox provider with 1.8 billion users worldwide, which makes it a good sample for most email marketers.

Read on to learn about GPMT and why you should regularly monitor GPMT's dashboards for insights on your sender reputation.

Why it's important to monitor your sender reputation

Your sender reputation is something like your email marketing program's credit score: you can't directly or manually change it, but you can follow best practices to ensure your "score" doesn't drop to a level that indicates to inbox providers that they should rout your messages to the spam folder or entirely block messages from being delivered.

The most important factor (of many) affecting your sender reputation is engagement from your contacts. Gmail's primary business concern is to inbox messages that their users want to see and to protect their users from unwanted content. Sending messages that contacts welcome by opening and clicking regularly is the baseline for a good sender reputation. GPMT provides dashboards that monitor your domain's spam rate and feedback loop issues that allow you to easily spot potential issues before they get bigger.

Passing authentication checks like SPF, DKIM, and DMARC is another critical factor affecting your sender reputation because messages that fail any of these checks are likely to be routed to spam. When you authenticate a sending domain, you're setting up these checks to pass. GPMT's authentication dashboard provides a valuable overview of your domain's authentication status which will allow you to catch any irregularities, like expired records, quickly before they can do much damage to your sender reputation.

How to interpret GPMT dashboards

When you log into GPMT, you'll see eight dashboards which each focus on a different aspect of your sender reputation.

Use this section to interpret and act on the information presented in each dashboard, and make sure to read Google's guide to each dashboard as well.

Compliance status

The compliance status dashboard is the newest addition to GPMT; it was created in 2024 to help senders ensure they comply with Gmail's 2024 bulk sender requirements.

The vast majority of Sendlane users are bulk senders (those who send ≥5000 messages per 24-hour period to Gmail), meaning you must check each of the eight areas of compliance listed in the compliance dashboard:

• SPF (handled by you) and DKIM (handled by Sendlane) authentication

• DNS records (handled by you; check your DNS setup if you receive errors in this category)

• Message formatting (handled by Sendlane; please reach out to Sendlane support or your customer success manager if you receive errors in this category)

• Encryption (handled by Sendlane; please reach out to Sendlane support or your customer success manager if you receive errors in this category)

• User-reported spam rate (the number of times an email is marked as spam divided by the number of sent emails; see 📄 Why is my email going to the spam folder?for next steps)

• DMARC authentication (handled by you if you used CNAME/MX/TXT records to verify your sending domain; ensure the TXT containing your DMARC protocol is set to p=none)

• One-click unsubscribe (Sendlane provides authentication for Gmail's embedded one click unsubscribe; please reach out to Sendlane support or your customer success manager if you receive errors in this category)

• Honor-unsubscribe (Sendlane provides permanent unsubscribe links in the footer of emails and doesn't allow email to be sent to contacts who unsubscribe; ensure you are not attempting to send to contacts who have unsubscribed)

See Google's help center for details on troubleshooting your compliance status dashboard items.

Spam rate

The spam rate dashboard shows the percentage of emails sent to Gmail users that were marked as spam, calculated as the number of emails that made it to a Gmail inbox but were marked as spam divided by the total number of emails that made it to a Gmail inbox.

Gmail's official guidance is to keep your spam rate below 0.3%, but we strongly recommend investigating potential issues if your spam rate reaches 0.1% or higher. A high spam rate means contacts are signaling that they do not want to receive your messages, which severely and negatively impacts your sender reputation.

Messages that land in the spam folder do not count towards your spam rate, but landing in the spam folder is a warning flag in and of itself. If your spam rate is suspiciously low, that could indicate that many of your emails are landing in the spam folder instead of the inbox.

See Google's help center for details on troubleshooting your spam rate.

IP reputation and domain reputation

GPMT's IP and domain reputation dashboard shows a high level reputation for your root domain, not just the subdomain you use for authenticated sending with Sendlane. This means that sending practices on your root domain and any other subdomains in use affect the Gmail placement of your email sent from Sendlane.

Google uses the following ratings for IP and domain reputation:

• Bad - History of sending a high volume of spam so regularly that virtually all email sent from this domain is marked as spam

• Low - History of sending a significant volume of spam with some legitimate email; email sent from this domain is likely to be marked as spam

• Medium - History of sending mostly legitimate email but sometimes spam too; most email from this domain makes it to the inbox

• High - History of sending legitimate email with low spam rates; email from this domain is rarely marked as spam

Gmail weighs domain reputation more heavily than IP reputation, and Sendlane has a team of dedicated deliverability professionals who monitor our IPs. If you're concerned about your IP reputation data, please reach out to Sendlane support or your customer success manager.

See 📄 Why is my email going to the spam folder? and Google's help center for details on troubleshooting your IP and domain reputation, making sure to investigate ALL email sent from your primary domain.

Feedback loop

Sendlane has implemented a feedback loop ID in the header of all emails which enables GPMT to log when emails get spam complaints. This allows you to see exactly which email had a spiked spam rate.

See Google's help center for details on troubleshooting your feedback loop dashboard.

Authentication

The authentication dashboard shows the success rate for your DKIM, SPF, and DMARC authentication. You should not see issues in this dashboard if you've verified your sending domain.

See Google's help center for more details on what to do if you receive low rates in any of the three authentication areas.

Encryption

Your emails' encryption is handled entirely by Sendlane. There are two main scenarios that can cause encryption issues:

1. Contacts forward your messages with a forwarding server that doesn't use TLS (uncommon but possible)

2. Someone is trying to spoof your emails

See more details about encryption at Google's help center. Reach out to Sendlane support or your customer success manager if you have concerns about encryption.

Delivery errors

The delivery errors dashboard shows the rate of rejection for messages authenticated by SPF or DKIM (with an authenticated sender profile, you're covered by both) which is calculated as the number of messages that were rejected or temporarily failed divided by the total number of all messages sent.

The dashboard also displays other potential errors:

• Rate limit exceeded - Gmail is suspicious of the volume and frequency of your sending; make sure you've properly warmed your sending domain and send at a consistent rate rather than sporadically making large sends.

• Suspected spam - Check your IP and domain reputation dashboard and your spam rate dashboard to dig into potential issues.

• Email content is possibly spammy - Gmail considers the content you're sending suspicious; review your content and 📄 Why is my email going to the spam folder? to determine where the problem lies.

• Bad or unsupported attachment - Sendlane doesn't allow for the direct attachment of files in an email, but if you've linked to a file Gmail can still detect it and cause an error.

• DMARC policy of the sender domain - If you receive this error it means you likely used CNAME records to authenticate your sending domain and there is likely a TXT record on your domain set to p=reject; to fix the error update this to p=none .

• Sending IP has a low reputation - You should not see this error because Sendlane's IPs are proactively monitored. Please reach out to to Sendlane support or your customer success manager if you receive this error.

• Sending domain has a low reputation - Check your domain reputation dashboard for more information.

• Domain is in one or more public RBLs - Your domain has appears in a public blocklist; reach out to Sendlane support or your customer success manager for recommended next steps.

• IP is in one or more public RBLs - You should never see this error because Sendlane's deliverability team actively monitors our IPs for RBL placement. If you do see this error, please reach out to Sendlane support or your customer success manager as soon as possible.

• Bad or missing PTR record - You should never see this error, please reach out to Sendlane support or your customer success manager if you do.