vsnetVBsrc

subscribe.aspx HTML Source

<%@ Page Language="vb" AutoEventWireup="false" Codebehind="subscribe.aspx.vb" Inherits="aspNetMXTest.subscribe"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<title>WebForm1</title>
</HEAD>
<body >

<form id="Form1" method="post" runat="server">
Please enter your email address to subscribe to our newsletter.
<br>
<input type=text id=txtEmailAddress runat=server NAME="txtEmailAddress"><input type=submit value="submit">
<asp:Literal ID=litMsg Runat=server></asp:Literal>

</form>

</body>
</HTML>

subscribe.aspx.vb Source

Imports aspNetMX
Public Class subscribe
    Inherits System.Web.UI.Page
    Protected WithEvents litMsg As System.Web.UI.WebControls.Literal
    Protected WithEvents txtEmailAddress As System.Web.UI.HtmlControls.HtmlInputText

#Region " Web Form Designer Generated Code "

    'This call is required by the Web Form Designer.
     Private Sub InitializeComponent()

    End Sub

    Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
        'CODEGEN: This method call is required by the Web Form Designer
        'Do not modify it using the code editor.
        InitializeComponent()
    End Sub

#End Region

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If Page.IsPostBack Then 'check email address
            'get an instance of MXValidate from the HttpCache
            Dim mx As MXValidate = GetMXObject()

            'check to see if the email address is valid
            Dim email As String = txtEmailAddress.Value
            Try
                Dim level As MXValidateLevel = mx.Validate(email, MXValidateLevel.MXRecords)
                If level = MXValidateLevel.MXRecords Then
                    'save to the database
                    SaveEmailAddress(email)

                    'write out a friendly message
                    litMsg.Text = "Thank you for subscribing"
                Else
                    litMsg.Text = "Please enter a valid email address."
                End If

            Catch
                'probably dns server not available, record the email address anyway, and double check when dns
                'server is back up
                SaveEmailAddress(email)

            End Try
        End If


    End Sub


    Private Sub SaveEmailAddress(ByVal EmailAddress As String)
        'this function is a placeholder and is would be used to save EmailAddress
        'to your data store.
    End Sub

    'check to see if the MX object is already stored in cache
    'if not create it. This will allow us to take advantage of MXValidate's built in MX Cache
    Private Function GetMXObject() As MXValidate
        Dim mx As MXValidate = CType(Cache("MXValidateObject"), MXValidate)

        If mx Is Nothing Then
            'create the mx object
            mx = New MXValidate()
            'increase the internal MX cache to be 1 day
            mx.CacheMXTimeOut = TimeSpan.FromDays(1.0)

            'add MXValidate to the HttpCache
            Cache("MXValidateObject") = mx
        End If

        Return mx
    End Function 'GetMXObject


End Class