> ## Documentation Index
> Fetch the complete documentation index at: https://docs-dev-docs-event-stream-action-templates.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Troubleshoot Email Provider Delivery Issues

> Diagnose and resolve Auth0 SMTP email provider failures, including authentication errors and provider-side throttling rejections that block delivery.

If you have email delivery issues with an external email provider, try the troubleshooting options below.

## View email notification errors

If you have configured an external email provider but are not receiving notifications that emails are being sent, verify your provider configuration details in Auth0.

To view log data regarding email notification errors, go to [Dashboard > Monitoring > Logs](https://manage.auth0.com/#/logs) and filter results on the **Failed Sending Notification** event type.

## Review your infrastructure and domain configuration

Configure your email provider with the following authentication standards:

* DomainKeys Identified Mail ([DKIM](http://dkim.org/))
* Sender Policy Framework ([SPF](https://datatracker.ietf.org/doc/rfc7208/))
* Domain-based Message Authentication, Reporting, and Conformance ([DMARC](https://dmarc.org/))

You can use several tools to review the settings of DNS records relating to DKIM, SPF, and DMARC. Built-in command line tools like `dig` and `nslookup` can help you diagnose your MX records and other common routing issues.

Online tools like [MXToolBox](https://mxtoolbox.com/) and [DNSChecker](https://dnschecker.org/all-tools.php) can also analyze settings related to authentication standards and are helpful in identifying misconfigurations or changes needed in your email settings.

<Warning>
  The tools above are not maintained by or affiliated with Auth0.
</Warning>

## Troubleshoot Microsoft 365 Exchange Online issues

If you use Microsoft 365 Exchange Online as your email provider, your emails may be quarantined if Exchange deems them as high risk. This can happen when emails route from an outside source.

If Exchange quarantines messages, an administrator can view the messages in a special inbox and determine if there is a DMARC alignment failure, causing the messages to appear as spam.

## Troubleshoot SendGrid issues

If you use SendGrid as your email provider, your emails may be suppressed if the recipient's email server rejects the message. To learn more, read [Different Types of Suppression in SendGrid Docs](https://docs.sendgrid.com/ui/sending-email/index-suppressions#different-types-of-suppressions).

In certain cases, SendGrid will [drop a message](https://www.twilio.com/docs/sendgrid/glossary/drops) to a specific email address in order to protect your sender reputation.

If you are using [passwordless authentication with email](/docs/authenticate/passwordless#email), ensure that the **From** email address value for your <Tooltip tip="Passwordless: Form of authentication that does not rely on a password as the first factor." cta="View Glossary" href="/docs/glossary?term=passwordless">passwordless</Tooltip> connection matches the **From** email address value you're using for SendGrid.

## Contact Auth0 support

If you review your custom email provider settings and ensure your domain implements DKIM, SPF, and DMARC protocols and your email delivery is still failing, you may need to contact the Auth0 support team for review.

Our support team can verify if your email provider receives messages and the error returned if they are not accepted. To learn more, read [Open and Manage Support Tickets](/docs/troubleshoot/customer-support/open-and-manage-support-tickets).