I have solved this problem.Sothat, if anyone got the same trouble like this, when you clicking " Testing" and got alert " Email Sever connection failed " you could think about That maybe sever which is running NSM is not allowed to send TCP/25 .
You can try by this :
CMD -- telnet ip_smtp_server 25.
If this screen is black and some informations display-- that mean everything is correct.Try again in NSM web page
If this screen is alert by not connect .... That may be firewall or Antivirus deny to send mail.
My case is Mcafee antivirus deny to send mail with NSM.
hope anyone can solve this problem like this