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Google Postmaster Tools (GPT) provides free insight into how Gmail sees your sending domain. It shows your domain reputation, spam rate, authentication pass rates, and delivery errors — data essential for diagnosing Gmail deliverability issues.

What Google Postmaster shows

MetricWhat it tells you
Domain reputationGmail’s trust score (High, Medium, Low, Bad)
IP reputationTrust score for sending IP addresses
Spam ratePercentage of emails Gmail users reported as spam
AuthenticationPass rates for SPF, DKIM, and DMARC
EncryptionPercentage of emails sent over TLS
Delivery errorsError codes and reasons for rejected messages

Setting up Google Postmaster Tools

1

Go to Google Postmaster Tools

Visit postmaster.google.com and sign in with a Google account.
2

Add your domain

Click the + button and enter your sending domain.
3

Verify ownership

Google provides a TXT or CNAME DNS record to verify domain ownership. Add it to your domain’s DNS.
4

Wait for data

Data appears once your domain sends sufficient volume to Gmail addresses (typically 100+ messages per day). Data may take 24-48 hours to populate.
Google Postmaster only shows data for email sent to Gmail and Google Workspace addresses. For Outlook, use Microsoft SNDS.

Interpreting the dashboard

Domain reputation

RatingMeaningAction
HighGmail trusts your domainMaintain current practices
MediumSome trust issuesReview recent campaigns for content or list quality issues
LowSignificant trust issuesClean your list, fix authentication, reduce volume
BadDomain is flaggedStop sending, clean list thoroughly, contact support

Spam rate

RateStatusAction
Below 0.05%ExcellentNo action needed
0.05%-0.10%AcceptableMonitor closely
0.10%-0.30%WarningInvestigate content and list quality
Above 0.30%CriticalPause campaigns and clean list immediately
Google requires bulk senders (5,000+ emails/day to Gmail) to maintain a spam rate below 0.10%. Exceeding this can result in permanent delivery degradation.

Action items by metric

Review your last 7-14 days of campaigns. High bounce rates, spam complaints, or sending to unengaged contacts are common causes. Clean your list, reduce volume, and focus on engaged contacts.
Ensure every email has a working unsubscribe link. Stop sending to contacts who have not engaged in 90+ days. Consider a re-engagement campaign.
Check your DNS records. SPF failures mean the sending IP is not in your SPF record. DKIM failures mean the signature is missing or invalid. See Email & SMTP setup.
Check the delivery errors tab for specific error codes. Common issues include rate limiting, authentication failures, and recipient address problems.

Connecting insights to HoopAI

  1. Low domain reputation — reduce campaign frequency, clean contact lists, verify addresses before sending
  2. High spam rate — review unsubscribe flow settings in Marketing > Emails > Campaigns (gear icon)
  3. Authentication failures — check DNS records for your dedicated sending domain in Settings > Email Services
  4. Rising delivery errors — slow down sending pace, check list quality, review bounce reports
Last modified on March 6, 2026