You can receive email message but can’t send email using DomainsFoundry SMTP. When you try sending Outlook returns an error message similar to the one shown below;

The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was ”. Subject: ”, Account: ”, Server: ”, Protocol: SMTP, Server Response: ‘550 … Relaying Denied’, Port: 25, Secure (SSL): No, Server Error: 550, Error Number: 0x800CCC79


  • Your ISP maybe blocking access to SMTP over the default port 25. This means your Outlook is unable to connect to the SMTP server to send your email.
  • SMTP authentication may not be enabled in your email client.


  1. Try changing the default SMTP port from 25. See [[How to change SMTP port number]]
  2. Check SMTP authentication is enabled in your email client.