‘Error 503: Bad sequence of commands’ indicates that the mail server requires authentication before allowing the email to be sent.
In most cases, the server is expecting valid credentials from the client, like a username and password, but doesn’t receive them. This error can often point to issues with the SMTP authentication settings on the client’s side, suggesting that they may be incorrectly configured or missing entirely.
Resolving the Error – Solution
To address this error, users should first check and ensure that their email client’s SMTP authentication settings are correctly configured. This typically involves confirming that the correct username and password are entered.
If you’re unsure about the right settings, consulting the email service provider’s documentation or contacting their support team can provide guidance.