Here are several steps you can take to resolve relay denied errors:
Authenticate: Ensure that you are using the correct SMTP authentication credentials. Most email servers require a username and password. Configure Server: Check the server settings to ensure that it is configured to allow relay from your IP address or domain. Whitelist IP: If the server supports it, ask the administrator to whitelist your IP address. Check Blacklists: Use tools to check if your IP address or domain is listed on any blacklists and take steps to remove them if necessary. Contact ISP: If your ISP is blocking relay, contact them to see if they can make an exception or provide an alternative solution.