This tutorial will show you how to use ASP.NET and VB.NET to download a list of emails using a POP3 server.
Using VB.NET to Retrieve List of Emails via POP3
This tutorial will show you how to use ASP.NET and VB.NET to download a list of emails using a POP3 server.
In this tutorial, we will give you an introduction into how
to use ASP.NET to login to a POP3 server and check your email. We will
be using the System.Net.Sockets namespace to utilize the TcpClient and
NetworkStream classes for this example.
The first thing we want to do is create our ASPX page. We will keep
it simple and add TextBoxes, a button and a Literal control to the page:
<table><tr><td>
POP3 Server: <asp:TextBox
ID="fld_Server" runat="server" /></td><td>Port:
<asp:TextBox ID="fld_Port" runat="server" Text="110" Columns="3"
/></td></tr>
<tr><td>Username:
<asp:TextBox ID="fld_Username" runat="server"
/></td><td>Password: <asp:TextBox ID="fld_Password"
runat="server" TextMode="Password" />
<asp:Button ID="btn_Connect" runat="server" Text="Connect" /><br />
<asp:Literal ID="lit_Status" runat="server" /> |
We are going to use the button to initiate the connection to the
POP3 server. We give the user the ability to input their own server,
and login credentials. We should now add the following handler in the
codebehind, along with the assembly reference:
Protected Sub btn_Connect_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btn_Connect.Click
End Sub |
We can use this handler for all of our code, seeing as we are just
connecting to the server and checking messages for this example. In a
real-world application, you may want to create a new class for the POP3
functionality.
We start by first create a new instance of the
TcpClient, and attempt to connect to the POP3 server. We also
instantiate a NetworkStream object, then we output the server response
to our Literal control:
Dim tcpClient As New TcpClient()
tcpClient.Connect(fld_Server.Text, Convert.ToInt32(fld_Port.Text))
Dim netStream As NetworkStream = tcpClient.GetStream()
Dim strReader As New System.IO.StreamReader(netStream)
lit_Status.Text = strReader.ReadLine() & "<br />" |
The next thing we will do is send our Username and Password to the server, and output the Server Response:
Dim WriteBuffer(1023) As Byte
Dim enc As ASCIIEncoding = New System.Text.ASCIIEncoding()
WriteBuffer = enc.GetBytes("USER " & fld_Username.Text & Constants.vbCrLf)
netStream.Write(WriteBuffer, 0, WriteBuffer.Length)
lit_Status.Text += strReader.ReadLine() & "<br />"
WriteBuffer = enc.GetBytes("PASS " & fld_Password.Text & Constants.vbCrLf)
netStream.Write(WriteBuffer, 0, WriteBuffer.Length)
lit_Status.Text += strReader.ReadLine() & "<br />" |
If the Username and Password are correct and verified by the Server, we will get a response starting +OK.
Now,
to retrieve a list of messages from the server, we first request using
the LIST command, and then we will want to loop through each message to
output:
WriteBuffer = enc.GetBytes("LIST" & Constants.vbCrLf)
netStream.Write(WriteBuffer, 0, WriteBuffer.Length)
Dim ListMessage As String
Do
ListMessage = strReader.ReadLine()
If ListMessage = "." Then
Exit Do
Else
lit_Status.Text += ListMessage & "<br />"
Continue Do
End If
|
We migrated our web sites to Server Intellect
over one weekend and the setup was so smooth that we were up and
running right away. They assisted us with everything we needed to do
for all of our applications. With Server Intellect's help, we were able to avoid any headaches!
Finally, to close the connection to the server, we send the command QUIT, and again, output the server response:
WriteBuffer = enc.GetBytes("QUIT" & Constants.vbCrLf)
netStream.Write(WriteBuffer, 0, WriteBuffer.Length)
lit_Status.Text += strReader.ReadLine() & "<br />" |
The full code-behind for this examples looks something like this:
Imports System.Net.Sockets
Partial Class _Default
Inherits System.Web.UI.Page
Protected Sub btn_Connect_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btn_Connect.Click
Dim tcpClient As New TcpClient()
tcpClient.Connect(fld_Server.Text, Convert.ToInt32(fld_Port.Text))
Dim netStream As NetworkStream = tcpClient.GetStream()
Dim strReader As New System.IO.StreamReader(netStream)
lit_Status.Text = strReader.ReadLine() & "<br />"
Dim WriteBuffer(1023) As Byte
Dim enc As ASCIIEncoding = New System.Text.ASCIIEncoding()
WriteBuffer = enc.GetBytes("USER " & fld_Username.Text & Constants.vbCrLf)
netStream.Write(WriteBuffer, 0, WriteBuffer.Length)
lit_Status.Text += strReader.ReadLine() & "<br />"
WriteBuffer = enc.GetBytes("PASS " & fld_Password.Text & Constants.vbCrLf)
netStream.Write(WriteBuffer, 0, WriteBuffer.Length)
lit_Status.Text += strReader.ReadLine() & "<br />"
WriteBuffer = enc.GetBytes("LIST" & Constants.vbCrLf)
netStream.Write(WriteBuffer, 0, WriteBuffer.Length)
Dim ListMessage As String
Do
ListMessage = strReader.ReadLine()
If ListMessage = "." Then
Exit Do
Else
lit_Status.Text += ListMessage & "<br />"
Continue Do
End If
Loop
WriteBuffer = enc.GetBytes("QUIT" & Constants.vbCrLf)
netStream.Write(WriteBuffer, 0, WriteBuffer.Length)
lit_Status.Text += strReader.ReadLine() & "<br />"
End Sub
|
|
