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How to browse and download the contents of a POP3 mailbox with Rebex Secure Mail for .Net

Introduction

Rebex Secure Mail for .Net provides a whole selection of ways that you can deal with email from within your program. Here we show how you can access a POP3 message box and retreive a list of the contents before downloading specific messages for viewing.

Detail

The C#.Net solution provided prompts for connection information relating to the POP3 server and mailbox to be accessed. It then displays a list of everything in the inbox and allows the user to view any message.

All of the UI controls are standard .Net controls and the work is done by the Rebex Secure Mail class libraries

Setup

Download the sample code using the above link and unzip it into a directory. Once the installation is complete you will find the C# sample code in the directory:

Rebex-SimplePOP3-C

and the VB.Net in the folder :

Rebex-SimplePOP3-VB

In the folder where you unpacked the ZIP file.

Configuration

The project makes 2 references Rebex.Mail and Rebex.Net.Pop3 and imports the namespaces Rebex.Mime, Rebex.Mail and Rebex.Net.

All the code for this solution is contained in class Form1. There are two main objects declared at class level _pop which is of type Rebex.Net.Pop3 and does most of the work, and _messages which is of type Pop3MessageCollection and stores the list of messages retreived.

These are instantiated in the constructor for Form1:

C#
    private Pop3 _pop;
    private Pop3MessageCollection _messages;
    public Form1()
    {
      InitializeComponent();
      this._pop = new Pop3();
    }

VB
    Private _pop As Pop3
    Private _messages As Pop3MessageCollection
    Public Sub New()
      InitializeComponent()
      Me._pop = New Pop3()
    End Sub

Getting a message list

On clicking the "Get Mail" button, a connection is made to the server specified in txtServer on the standard POP3 port, 110 by the Connect() method of _pop3. A login is then initiated using the Login() method which passes username & password.

C#
    private void btnGet_Click(object sender, EventArgs e)
    {
      try
      {
        //Connect to the server
        this._pop.Connect(txtServer.Text, 110);
        this._pop.Login(txtUsername.Text, txtPassword.Text);
        .
        .

VB
    Private Sub btnGet_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGet.Click
      Try
        'Connect to the server 
        Me._pop.Connect(Me.txtServer.Text, 110)
        Me._pop.Login(Me.txtUsername.Text, Me.txtPassword.Text)
        .
        .

The messages can now be retreived from the mailbox using the GetMessageList() method of _pop3. This returns a MessageCollection object which is then iterated and a MessageInfo is retreived for each message via the GetMessageInfo() method of _pop3. Each MessageInfo object is then used to load the listView for display.

C#
        //get the list of message
        this._messages = _pop.GetMessageList();

        //Load the messages into the listView
        foreach (Pop3MessageInfo message in this._messages)
        {
          Pop3MessageInfo m = this._pop.GetMessageInfo(message.SequenceNumber, Pop3ListFields.FullHeaders);

          if (m.HeadersParsed)
          {
            string subject = (m.Subject != null) ? m.Subject : "n/a";
            string date = (m.Date != null) ? m.Date.LocalTime.ToString("yyyy-MM-dd HH:mm:ss") : "n/a";
            ListViewItem item = new ListViewItem(m.From.ToString());
            item.Tag = m;
            item.SubItems.Add(subject);
            item.SubItems.Add(m.Length.ToString());
            item.SubItems.Add(date);
            this.listView.Items.Add(item);

VB
        'get the list of message 
        Me._messages = _pop.GetMessageList()

        'Load the messages into the listView 
        For Each message As Pop3MessageInfo In Me._messages
          Dim m As Pop3MessageInfo = Me._pop.GetMessageInfo(message.SequenceNumber, Pop3ListFields.FullHeaders)

          If m.HeadersParsed Then
            Dim subject As String = IIf((m.Subject IsNot Nothing), m.Subject, "n/a")
            Dim [date] As String = IIf((m.[Date] IsNot Nothing), m.[Date].LocalTime.ToString("yyyy-MM-dd HH:mm:ss"), "n/a")
            Dim item As New ListViewItem(m.From.ToString())
            item.Tag = m
            item.SubItems.Add(subject)
            item.SubItems.Add(m.Length.ToString())
            item.SubItems.Add([date])
            Me.listView.Items.Add(item)

Note that each Pop3MessageInfo object returned in the collection is stored in the Tag property of the associated ListViewItem. This is useful when selecting a message to view.

Viewing a message

A message is viewed by double clicking on a line in the listView. This causes the MessageInfo object to be retreived from the Tag property.

The SequenceNumber property of the message is then used by the GetMessage method of _pop3 to retreive the full message from the server into a MimeMessage object.

This is then cast as a MailMessage and the BodyText property is used to display the message body in the textbox txtMessage.

C#
          //Get the message info item back out of the listView tag property
          Pop3MessageInfo m = (Pop3MessageInfo)selCol[0].Tag;
          
          //Get the sequence number and use it to retreive the message
          int sequenceNumber = this._messages.Find(m.UniqueId).SequenceNumber;
          MemoryStream buffer = new MemoryStream();
          this._pop.GetMessage(sequenceNumber, buffer);
          
          //Download the message stream into a MIME object
          buffer.Position = 0;
          byte[] raw = buffer.ToArray();
          MimeMessage mime = new MimeMessage();
          mime.Load(buffer);
          
          //Cast the mime object into a message to access the body text
          MailMessage message = (MailMessage)mime;
          txtMessage.Text = message.BodyText.Replace("\n", "\r\n");

VB
          'Get the message info item back out of the listView tag property 
          Dim m As Pop3MessageInfo = DirectCast(selCol(0).Tag, Pop3MessageInfo)

          'Get the sequence number and use it to retreive the message 
          Dim sequenceNumber As Integer = Me._messages.Find(m.UniqueId).SequenceNumber
          Dim buffer As New MemoryStream()
          Me._pop.GetMessage(sequenceNumber, buffer)

          'Download the message stream into a MIME object 
          buffer.Position = 0
          Dim raw As Byte() = buffer.ToArray()
          Dim mime As New MimeMessage()
          mime.Load(buffer)

          'Cast the mime object into a message to access the body text 
          Dim message As MailMessage = CType(mime, MailMessage)
          Me.txtMessage.Text = message.BodyText.Replace("" & Chr(10) & "", "" & Chr(13) & "" & Chr(10) & "")

Conclusion

This simplistic solution demonstrates how Rebex Secure Mail for .Net can be used to retreive the contents of a mailbox from within a program. The capabilities of this component go much further and there are considerably more sophisticted samples available on the Rebex web site, just follow the link below.