‘Error 504: Command Parameter Not Implemented’ typically occurs when there’s a mismatch between the SMTP command parameters used by the sender and those accepted by the recipient’s Message Transfer Agent (MTA). This error occurs when the MTA does not recognize or support a specific command or its parameters.
It can also be a gateway timeout issue, indicating delayed responses from an upstream server or network connectivity problems.
Resolving the Error – Solution
To address this error, review the SMTP command parameters of the failed email and adjust them to match the recipient’s MTA configuration. Alternatively, reconfigure the MTA to accept those parameters, or resend the email without the problematic command.
If it’s a timeout issue, try sending the email later when server traffic is lower, or check your network connection for any issues.
That’s it! Now you know the common causes of the 504 error and how to resolve it.
If you’d like to learn how to troubleshoot other common errors, check out the following docs: