Is it possible to send mail through my web application without having SMTP server? For example, the mail will be send through my existing hotmail account or yahoo account to ppl who registered in my web application. If it is viable, please provide me some resources on the method...Thanks in advance:)

i dont think You can login automatically to your yahoo account compose a mail and send using an asp.net application.

But you can set the from field of mail object to what ever you want,
then whats the need to use yahoo/hotmail account?

I am developing a web app that will send mail to lecturer... I am wondering whether is there any alternative way to do this. I have totally no idea about SMTP setup...

Yahoo will not allow to use their service like that .

Check out system.net.mail or system.web.mail..
i think you will get what you want.