Send & Receive Issues

Fix Emails Sent to Gmail Going to Spam Despite DKIM and DMARC

Steve K Sep 30, 2026 868 views

Question details

Business emails are being routed to Gmail's spam folder despite having active DKIM and DMARC authentication and valid recipient addresses.

How to Fix Emails Sent to Gmail Going to Spam Despite DKIM and DMARC

Product: Email SMTP Server
Device & OS: not provided
Scenario: Sending outbound business emails to Gmail recipients through an SMTP relay.
Observed behavior: Emails bypass the recipient's inbox and land directly in the spam folder, indicating potential issues with third-party connector configuration, reputation, or strict Gmail filtering.

Before you start

Ensure you have administrative access to your domain's DNS settings, your SMTP relay configuration portal, and Google Postmaster Tools before making structural changes.

Solution 1Recommended

Verify SPF Inclusion and SMTP Relay Configurations

Correctly configuring your SPF record to include your SMTP relay ensures Gmail recognizes your third-party sender as legitimate.

Even with DKIM and DMARC enabled, if your SPF record lacks the IP address or domain of your SMTP relay, Gmail may flag the messages as suspicious.

A misconfigured SMTP connector can also cause authentication alignment failures, dropping the email's trust score.

Check SPF records

Log in to your DNS hosting provider and verify that your SPF record explicitly includes the domain or IP addresses of your third-party SMTP relay service (e.g., include:_spf.yourrelay.com).

Verify DKIM alignment

Ensure the SMTP relay is signing outgoing emails with a DKIM key that correctly matches your sending domain, rather than the relay provider's default domain.

Review DMARC reports

Analyze your DMARC XML reports to identify which specific emails are failing SPF or DKIM alignment when routed through the SMTP connector.

Verify SPF Inclusion and SMTP Relay Configurations

DNS Propagation: Remember that any updates made to SPF, DKIM, or DMARC records in your DNS may take up to 48 hours to fully propagate globally.

Solution 2

Monitor Sender Reputation via Google Postmaster Tools

Gmail heavily relies on domain and IP reputation, user engagement, and content analysis beyond basic email authentication protocols.

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Frequently Asked Questions

Why does Gmail flag my emails as spam if DMARC is set to 'reject'?

DMARC only proves that the email legitimately came from your domain. If your domain or IP address has a poor sending reputation, or if the email content contains spam-like characteristics, Gmail's proprietary filters will still route the message to the spam folder.

Does my SMTP relay need its own SPF record?

The domain in the 'Return-Path' (or Envelope-From) must have an SPF record that authorizes the SMTP relay's IP addresses. If you use a third-party relay, you must include their SPF mechanism in your own domain's DNS record.

How can email content affect Gmail deliverability despite good authentication?

Gmail analyzes the actual content of the email, including links, images, and keywords. Using URL shorteners, excessive promotional language, or linking to domains that are already blacklisted can trigger spam filters even if SPF, DKIM, and DMARC perfectly align.

Outlook & Email Problems