--- description: Email Security for Zero Trust. title: Email Security image: https://developers.cloudflare.com/og-docs.png --- [Skip to content](#main-content) > Documentation Index > Fetch the complete documentation index at: https://developers.cloudflare.com/cloudflare-one/llms.txt > Use this file to discover all available pages before exploring further. # Email Security Last updated Aug 24, 2026|Copy as Markdown|[View as Markdown](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/cloudflare-one/troubleshooting/email-security/index.md)|[Agent setup](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/agent-setup/) Review common troubleshooting scenarios for Cloudflare Email Security. ## Email headers and attributes Email Security identifies threats using detections that result in a final disposition. You can inspect email headers to understand why a specific disposition was applied. | Attribute | Description | | ------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | CUSTOM\_BLOCK\_LIST | Matches a value defined in your custom block list. | | NEW\_DOMAIN\_SENDER | The email was sent from a newly registered domain. | | NEW\_DOMAIN\_LINK | The email contains links to a newly registered domain. | | ENCRYPTED | The email message is encrypted. | | BEC | The sender address is in your [impersonation registry](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/cloudflare-one/email-security/settings/detection-settings/impersonation-registry/). | ## Detections and reclassification ### Handle a false positive A false positive occurs when a legitimate email is incorrectly flagged as malicious or spam. **Solution**: 1. In the Email Security dashboard, go to **Investigation**. 2. Find the email and select **Submit for reclassification**. 3. Choose the correct disposition (for example, `Clean`). 4. To prevent future blocks, add the sender to your [Acceptable Senders](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/cloudflare-one/email-security/settings/detection-settings/allow-policies/) list. ### Handle a false negative A false negative occurs when a malicious email is not detected by Email Security. **Solution**: 1. Ensure the email actually passed through Email Security by checking for the `X-CFEmailSecurity-Disposition` header. 2. Submit the email for reclassification in the dashboard. This is the preferred method for reporting missed detections. ## Authentication errors ### DMARC failures Email Security may mark an email as **SPAM** if it fails DMARC authentication and the sending domain has a `p=reject` or `p=quarantine` policy. **Solution**: * Ask the sender to fix their DMARC/SPF/DKIM records. * Configure an [Acceptable Sender](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/cloudflare-one/email-security/settings/detection-settings/allow-policies/) entry to suppress the failure for that specific sender. ## Delivery issues ### Emails are delayed or not arriving If emails are not being delivered or are arriving with significant latency: 1. **Check MX records**: Ensure your [MX records](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/cloudflare-one/email-security/setup/) are correctly configured and pointing to Cloudflare. 2. **Verify connectivity**: From your sending mail server, verify you can connect to Cloudflare's mailstream endpoints on port 25. 3. **Check outbound logs**: In the dashboard, use the **Mail Trace** feature to confirm if Email Security successfully delivered the email to your downstream mail server (for example, Google Workspace or Microsoft 365). --- ## More Email Security resources For more information, refer to the full Email Security documentation. [Email Security troubleshooting ❯](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/cloudflare-one/email-security/troubleshooting/) Was this helpful? YesNo ## On this page [![](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/_astro/logo.te5VL_aD.svg)Docs](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/) ```json {"@context":"https://schema.org","@type":"WebPage","@id":"https://developers.cloudflare.com/cloudflare-one/troubleshooting/email-security/#page","headline":"Email Security · Cloudflare One docs","description":"Email Security for Zero Trust.","url":"https://developers.cloudflare.com/cloudflare-one/troubleshooting/email-security/","inLanguage":"en","image":"https://developers.cloudflare.com/og-docs.png","dateModified":"2026-08-24","publisher":{"@type":"Organization","name":"Cloudflare","description":"One platform for your apps, agents, and workforce. 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