Email Error Messages
SMTP error codes and solutions
Understand the errors that occur during email sending and learn how to fix them. Explanation and troubleshooting guide for the most common SMTP error codes.
Quick reference
4xxTemporary errors
The server will automatically retry. Usually no action required.
5xxPermanent errors
The email cannot be delivered. Fix required before resending.
AuthAuthentication errors
SPF, DKIM, DMARC issues. Check DNS settings.
Prevent errors!
Test your email settings before running into problems. MailAudit helps identify potential error sources.
Start a test