validar email desde un campo texbox vb.net (funtion invalidEmail)

    Public Function IsValidEmail(ByVal email As String) As Boolean
        If email = String.Empty Then Return False
        ' Compruebo si el formato de la dirección es correcto.

        Dim re As Regex = New Regex("^[a-zA-Z][\w\.-]*[a-zA-Z0-9][\w\-]@[a-zA-Z0-9][\w\.-_]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]{2,4}$")
        Dim m As Match = re.Match(email)
        Return (m.Captures.Count <> 0)
    End Function