Send & Receive Issues

How to Fix Gmail Email Rejections Due to Low Sending-Domain Reputation

Phi Hung Vo Oct 10, 2026 871 views

Question details

Users are unable to successfully deliver emails to Gmail and Google Workspace recipients because their messages are blocked by a 550 5.7.1 error due to poor domain reputation.

How to Fix Gmail Rejections Caused by Low Sending-Domain Reputation

Product: Google Workspace / Gmail
Device & OS: not provided
Scenario: Sending outbound emails or mass communications to Gmail and Google Workspace users.
Observed behavior: Emails are continuously rejected and returned with a 550 5.7.1 error message stating the sending domain has a very low reputation, despite SPF and DKIM being configured.

Before you start

Verify that your mail server's IP address is not currently listed on any major public email blacklists and pause any automated mass email campaigns before beginning the troubleshooting process.

Solution 1Recommended

Analyze and Monitor Reputation with Google Postmaster Tools

Set up Google Postmaster Tools to identify the exact cause of your poor domain reputation and track your spam and delivery rates directly from Google's perspective.

Google provides a dedicated platform to help domain owners track data on high-volume email sending. By registering your domain, you can uncover metrics regarding IP reputation, authentication errors, and user spam reports.

Access Postmaster Tools

Navigate to postmaster.google.com and sign in with a valid Google account.

Add Your Sending Domain

Click the '+' button in the bottom right corner, enter your exact sending domain, and click 'Next'.

Verify Domain Ownership

Copy the provided TXT record and add it to your domain's DNS configuration via your domain registrar. Once propagated, click 'Verify' in Postmaster Tools.

Review Reputation Dashboards

Navigate through the 'Domain Reputation', 'Spam Rate', and 'Authentication' tabs to pinpoint exactly when the reputation dropped and what caused the spikes.

Analyze and Monitor Reputation with Google Postmaster Tools

Data Availability: Postmaster Tools requires a certain daily volume of email traffic to generate data. If your sending volume is very low, the dashboards may appear blank.

Solution 2

Ensure Strict SPF, DKIM, and DMARC Alignment

Even if SPF and DKIM are set up, they must strictly align with your 'From' address and be enforced by a DMARC policy to establish trust with Gmail.

Solution 3

Audit Mailing Lists and Secure Compromised Accounts

Spam complaints and compromised sender accounts are the most common contributors to a sudden, severe drop in domain reputation.

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Frequently Asked Questions

How long does it take to recover a bad domain reputation in Gmail?

Depending on the severity of the reputation drop, it typically takes 2 to 4 weeks of consistent, high-quality sending behavior (low spam rates, no bounces, and correct authentication) for Google's algorithms to improve a domain's reputation.

What does the 550 5.7.1 error code mean?

The 550 5.7.1 error is a standard SMTP reply indicating that the recipient's mail server refused to accept the message. In the context of Gmail and Google Workspace, this usually means the sender's IP or domain has a poor reputation, is blacklisted, or lacks the required SPF/DKIM authentication.

Can I bypass the domain reputation check by simply changing my server's IP address?

No. While changing your IP address might reset your IP reputation, Google heavily weighs domain reputation as well. Changing IPs without fixing the underlying authentication issues or spam complaints will result in your domain continuing to be rejected.

Why are my emails blocked even though my SPF and DKIM pass?

Passing SPF and DKIM confirms your identity, but it does not guarantee delivery if your domain has a history of high spam complaints, sending to invalid addresses, or acting suspiciously. Authentication is required, but maintaining a good sender reputation is equally important.

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