SMTP Error 502 is a permanent or "5xx" error code returned by a mail server, indicating the rejection of a command or request that it does not support or cannot process. This error signifies the server's refusal of the email message or command due to incompatibility or limitations.

What's Causing This Error?

SMTP Error 502 may result from various factors:

• Unsupported commands: The sender's email client or server may issue SMTP commands that the recipient server does not recognize or support.
• Configuration issues: The recipient server may have specific configurations or restrictions causing it to reject certain types of emails or commands.
• Policy limitations: The server's policies or restrictions may lead to SMTP Error 502 if the sender's request or email content does not comply.

How to Fix SMTP Error 502?

To address SMTP Error 502:

• Check email client or server settings: Ensure that the email client or server uses compatible SMTP commands and follows best practices.
• Review recipient server policies: Consult the recipient server's documentation or contact its administrators to understand policies and limitations, ensuring compliance.
• Test and adjust: If encountering SMTP Error 502, test different configurations or SMTP commands to find a compatible method for communicating with the recipient server.

SMTP Error 502 Examples:

SMTP Error 502 in phpmailer:

• "502 5.5.1 Command not recognized. Check your SMTP command."
• "502 5.3.2 Configuration restrictions prevent this request. Contact the administrator for assistance."

SMTP Error 502 in Jenkins:

• "502 5.7.0 Policy limitations prevent email delivery. Review and adjust your email content."
• "502 5.4.1 Incompatible SMTP command. Ensure your client or server is configured correctly."

‍