Expanding on Ehsan's Answer....
If you are using .Net framework 4.5 then you can have a simple method to verify email address using EmailAddressAttribute Class in code.
private static bool IsValidEmailAddress(string emailAddress)
{
return new System.ComponentModel.DataAnnotations
.EmailAddressAttribute()
.IsValid(emailAddress);
}
If you are considering REGEX to verify email address then read:
I Knew How To Validate An Email Address Until I Read The RFC By Phil Haack