what is the settings required for mail sending through asp.net (in my code thier nither throwing the error nor the mail is going)?

hi All

 i had created the web application, in whcih i will send mail. previously i was able to send the mail without probem.but if run the same application now  (in debug mode, previously also it was in debug mode) mail is not going, niether it is throwing any error. ithink some sort of setiing is missing in my PC? meanwhile the OS is reinstalled in my PC and may be some setting is not done after the OS Reinstallation

 could any one please tell where to find that setting or how to set the setting so that mail can be send from my  web application?

below is the code using for sending the mail.

Dim sContent As String
Dim objMessage As Mail.Mail ...