SMTP Error 550 5.1.2

What This Error Means

This error occurs when the email address format is incorrect or the mailbox cannot accept mail. Unlike 5.1.1, this often indicates a syntax or formatting issue rather than a non-existent user.

Common Causes

• 1Invalid characters in the email address
• 2Malformed email address syntax
• 3The mailbox is configured to reject incoming mail
• 4Domain-level routing issues

How to Fix It

• 1Check the email address format for invalid characters
• 2Verify the domain's MX records are properly configured
• 3Contact the recipient through alternative means to get correct address
• 4Use email validation to catch formatting issues before sending