I found following code from this link.
https://msdn.microsoft.com/en-us/library/01escwtf(v=vs.80).aspx
Function IsValidEmail(strIn As String) As Boolean
' Return true if strIn is in valid e-mail format.
Return Regex.IsMatch(strIn, "^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$")
End Function
I dont know how to use above code. I mean how to call above code?