The best way to test Windows Server for the sending/relaying of email is using the Microsoft command line utility, smtpdiag.exe. Download it from the Microsoft site and extract the file.
From the command line, type the following command:
smtpdiag.exe "[sender@domain.com]" "[receiver@domain.com]" /vSMTPDiag will then provide you with detailed information regarding your present configuration for the sending/relaying of email on your Server.
