Mã: Public Function IsEmail(ByVal Email As String) As Boolean Dim strEmail As String = "^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}" & "\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\" & ".)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$" Dim re As New Regex(strEmail) If re.IsMatch(Email) Then Return (True) Else Return (False) End If End Function Import thêm thư viện System.Text.RegularExpressions