Microsoft® Visual Basic® .NET Programmer's Cookbook

Retrieve E-Mail Through POP3

Problem

You want to retrieve messages from a POP3 mail server.

Solution

Create a dedicated class that sends POP3 commands over a TCP connection.

Discussion

POP3 is a common e-mail protocol used to download messages from a mail server. POP3, like many Internet protocols, defines a small set of commands that are sent as simple ASCII-encoded messages over a TCP connection (typically on port 110).

Here’s a listing of a typical POP3 dialogue, starting immediately after the client makes a TCP connection:

Server sends:+OK <[e-mail]> Client sends:USER <UserName> Server sends:+OK Client sends:PASS <Password> Server sends:+OK Client sends:LIST Server sends:+OK Server sends:<Message list terminated by a period> ...