sending mail through system.net.mail in c#.............its giving innerexception

i have similar issue in c#

It gives error as inner exception.Please help me with this

 

 This is the code which i used in my application

 
System.Net.Mail.MailMessage objEmail = new System.Net.Mail.MailMessage();
objEmail.To.Add(tomail);
objEmail.From = new System.Net.Mail.MailAddress("myemail@gmail.com");objEmail.Subject = "Email From www.YourDomain.com"; < ...