Step 6: Test your new mail relay server! Before you proceed to install Mail essentials, verify that your new mail relay server is working correctly. 1. Test IIS 5 SMTP inbound connection of your mail relay server by sending a mail from an external account to an internal user (you can use hotmail, if you don't have an external account available). Verify that the mail client received the email. 2. Test IIS 5 SMTP outbound connection of your mail relay server by sending a mail to an external account from an internet email client. Verify that the external user received the email. Note: Instead of using an email client, you can use Telnet and manually send an email. This will give you more troubleshooting information. Here is the link to the Microsoft KB article how to do it: http://support.microsoft.com/support/kb/articles/Q153/1/19.asp