If you encounter the error message shown below while attempting to send emails through your server, you need to enable SMTP Authentication.
"The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was 'user@domain.com'. Subject 'Subject', Account: 'mail.yourdomain.com', Server: 'mail.yourdomain.com', Protocol: SMTP, Server Response: '550 5.7.1 ... Relaying denied', Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC79"
This error message occurs due to security settings in place to prevent spammers from using your server to send emails. To resolve this issue, you need to enable SMTP Authentication to send SMTP emails.
If you're using Outlook, follow these steps:
1. Click on "Tools" and select "Accounts."
2. Choose the account through which you're trying to send emails.
3. Click on "Properties."
4. Select the "Servers" tab.
5. Check the box that says, "My server requires authentication."
