Retrieving email from POP3 server using VB.NET
This article will demonstrate how using the Email Factory for .NET Pop component you can retrieve emails from a POP3 server using VB.NET. To see what else Email Factory for .NET has to offer Download a FREE 30 day Email Factory for .NET Evaluation.
The Email Factory for .NET Pop component provides methods for communicating with an POP3 server. Using the Email Factory for .NET components retrieving email from a POP3 or IMAP server is a very simple task. For the purposes of this article we will focus on using the POP3 protocol. Details of using the IMAP protocol to retrieve email are very much the same, the main difference being that the Pop class is used instead of the Imap class.
The process for establishing an interactive session with an POP3 server using the Email Factory for .NET component is as follows:
- Creating a new Pop instance with events
- Establishing a connection
- Retrieving one or more Email messages
- Saving attachments to disk
- Reading message attributes
- Releasing a connection
Each of these processes is described in the sections below.
Before creating a new Pop instance, ensure that the Jscape.Email scope is defined in your Imports statements, and that the Jscape.Email.dll is referenced in your project. Refer to Getting Started in the Email Factory for .NET Help for more information about adding the Jscape.Email.dll reference to your projects.
The Pop component may publish one or more events during the lifetime of an Pop session. Any object that subscribes to events published by the Pop component can receive and process the following events.
- The
ConnectedEvent is fired by the Pop instance once a connection to the POP server has been established.
- The
DisconnectedEvent is fired by the Pop instance once the connection to the POP server has been released.
- The
CommandSentEvent is fired by the Pop instance for each command sent to the POP server.
- The
DataReceivedEvent is fired by the Pop instance for each response received from the POP server.
- The
MessageRetrievedEvent is fired by the Pop instance for each message retrieved from the POP server.
After you have the Jscape.Email.dll reference added to your project, you can define a Pop instance with Events.
Dim WithEvents myPop As Pop = Nothing
Create a new Pop instance providing the POP3 server hostname, username, and password as arguments.
myPop = New Pop("hostname", "username", "password")
Now you can create the event handler methods you previously defined when subscribing to the Pop events.
Public Sub OnConnected(ByVal sender As Object, ByVal e As PopConnectedEventArgs) Handles myPop.ConnectedEvent
Console.WriteLine("Connected to {0}", e.Host)
End Sub
Public Sub OnDisconnected(ByVal sender As Object, ByVal e As PopDisconnectedEventArgs) Handles myPop.DisconnectedEvent
Console.WriteLine("Disconnected.")
End Sub
Public Sub OnDataReceived(ByVal sender As Object, ByVal e As PopDataReceivedEventArgs) Handles myPop.DataReceivedEvent
Console.WriteLine("Response: " + e.Response)
End Sub
Public Sub OnCommandSent(ByVal sender As Object, ByVal e As PopCommandSentEventArgs) Handles myPop.CommandSentEvent
Console.WriteLine("Command: " + e.Command)
End Sub
Public Sub OnMessageRetrieved(ByVal sender As Object, ByVal e As PopMessageRetrievedEventArgs) Handles myPop.MessageRetrievedEvent
Console.WriteLine("Command: " + e.Message.Subject)
End Sub
Once a Pop instance has been created and subscribed to the Pop events you may establish a connection to the POP server by invoking the Connect() method.
myPop.Connect()
Upon establishing a connection to a POP server you can retrieve all messages in the Pop account mailbox by invoking the GetMessages method. Any messages found are returned as an Enumeration.
Dim message As EmailMessage = Nothing
Dim e As IEnumerator = myPop.GetMessages()
While (e.MoveNext())
message = e.Current
End While
Additionally, you can retrieve a message in the account mailbox by invoking the GetMessage method and passing the one-based message ID as an argument.
' get the first message
Dim message As EmailMessage = myPop.GetMessage(1)
Once you have retrieved an email message you can then retrieve any attachments and save them to disk.
Dim mc As Int32 = 0
Dim ac As Int32 = 0
Dim e As IEnumerator = myPop.GetMessages()
Dim message As EmailMessage = Nothing
While (e.MoveNext())
mc = mc + 1
message = e.Current
Dim a As IEnumerator = message.GetAttachments()
While (a.MoveNext())
ac = ac + 1
attachment = a.Current
' get name of attached file
Dim filename As String = attachment.GetFilename()
if (filename.Length = 0) Then
filename = "att" & mc & "_" & ac & ".txt"
End If
' get data for attached file
Dim data As Byte() = attachment.GetFileData()
' process the attachment
Dim fs As New FileStream(filename, FileMode.Open, FileAccess.Write)
Dim w As New BinaryWriter(fs)
w.Write(data, 0, data.Length)
fs.Close()
End While
End While
The Email Factory for .NET Pop component contains methods and properties for reading message attributes, such as the Subject, Body, Content-Type, From address, etc.
Dim e As IEnumerator = myPop.GetMessages()
Dim message As EmailMessage = Nothing
While (e.MoveNext())
message = e.Current
' display message subject
Console.Write(message.Subject & vbTab)
' display From address
Console.Writeline(message.From)
' display message content type
Console.Writeline(message.GetContentType())
}
To release an established connection simply invoke the Disconnect() method as follows:
myPop.Disconnect();
The source code for this article is available for download and for viewing.
View example source code
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