# Troubleshooting

This section covers common issues you might encounter when using Mailtrap Email API/SMTP and their solutions.

### Common Issues

#### Authentication & Authorization

* [Unauthorized Error (401 Code)](/email-api-smtp/help/troubleshooting/unauthorized-401-error.md) - Issues with API credentials, tokens, or domain verification
* [Sending from Domain Not Allowed](/email-api-smtp/help/troubleshooting/sending-from-domain-not-allowed.md) - Domain verification and FROM address problems

#### Email Delivery

* [From Header Domain Mismatch](/email-api-smtp/help/troubleshooting/from-header-domain-mismatch.md) - Fixing FROM header configuration issues

#### SSL & Security

* [SSL Cipher Overlap Error (Error 1001)](/email-api-smtp/help/troubleshooting/ssl-cipher-overlap-error.md) - Custom tracking domain SSL certificate issues

#### Third-Party Services

* [MS Office 365 Quarantine](/email-api-smtp/help/troubleshooting/ms-office-365-quarantine.md) - Mailtrap emails going to Office 365 quarantine

### Need More Help?

If you don't find the solution to your problem here:

1. Check our [FAQs](/email-api-smtp/help/faqs.md) for general questions
2. Contact support at <support@mailtrap.io>
3. Visit the API documentation for technical details


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