How do I validate email address formatting with the .NET Framework?

Question

I want a function to test that a string is formatted like an email address.

What comes built-in with the .NET framework to do this?

This works:

Answer 1

Another function to check that the email is valid or not :

Public Function ValidEmail(ByVal strCheck As String) As Boolean
    Try
        Dim bCK As Boolean
        Dim strDomainType As String
        Const sInvalidChars As String = "!#$%^&*()=+{}[]|\;:'/?>,< "
        Dim i As Integer
        'Check to see if there is a double quote
        bCK = Not InStr(1, strCheck, Chr(34)) > 0
        If Not bCK Then GoTo ExitFunction
        'Check to see if there are consecutive dots
        bCK = Not InStr(1, strCheck, "..") > 0
        If Not bCK Then GoTo ExitFunction
        ' Check for invalid characters.
        If Len(strCheck) > Len(sInvalidChars) Then
            For i = 1 To Len(sInvalidChars)
                If InStr(strCheck, Mid(sInvalidChars, i, 1)) > 0 Then
                    bCK = False
                    GoTo ExitFunction
                End If
            Next
        Else
            For i = 1 To Len(strCheck)
                If InStr(sInvalidChars, Mid(strCheck, i, 1)) > 0 Then
                    bCK = False
                    GoTo ExitFunction
                End If
            Next
        End If

        If InStr(1, strCheck, "@") > 1 Then 'Check for an @ symbol
            bCK = Len(Left(strCheck, InStr(1, strCheck, "@") - 1)) > 0
        Else
            bCK = False
        End If
        If Not bCK Then GoTo ExitFunction
        strCheck = Right(strCheck, Len(strCheck) - InStr(1, strCheck, "@"))
        bCK = Not InStr(1, strCheck, "@") > 0 'Check to see if there are too many @'s
        If Not bCK Then GoTo ExitFunction
        strDomainType = Right(strCheck, Len(strCheck) - InStr(1, strCheck, "."))
        bCK = Len(strDomainType) > 0 And InStr(1, strCheck, ".") < Len(strCheck)
        If Not bCK Then GoTo ExitFunction
        strCheck = Left(strCheck, Len(strCheck) - Len(strDomainType) - 1)
        Do Until InStr(1, strCheck, ".") <= 1
            If Len(strCheck) >= InStr(1, strCheck, ".") Then
                strCheck = Left(strCheck, Len(strCheck) - (InStr(1, strCheck, ".") - 1))
            Else
                bCK = False
                GoTo ExitFunction
            End If
        Loop
        If strCheck = "." Or Len(strCheck) = 0 Then bCK = False
ExitFunction:
        ValidEmail = bCK
    Catch ex As ArgumentException
        Return False
    End Try
    Return ValidEmail
End Function

How to use it:

Private Sub TextBox2_KeyDown(sender As Object, e As KeyEventArgs) Handles TextBox2.KeyDown
    If e.KeyCode = Keys.Enter Then
        If TextBox2.Text = "" Then
            MsgBox("Write Down Your email and Press Enter") : TextBox2.Select()
        Else

            If ValidEmail(TextBox2.Text) Then ' to check if the email is valid or not
                   'do whatever
            Else
                MsgBox("Please Write Valid Email")
                TextBox2.Select()
            End If
        End If
    End If
End Sub