Making a POP3 Client
Well, lets start with the basics first. POP3 stands for Post Office Protocol version 3. It is (along with IMAP) the standard protocol for receiving email across a network. You only need several things to connect. These include a valid username and password, and the address of the POP server. For those of you using a dial up connection, this address will probably look something like this:
Where ispname is the name of your Internet Service Provider. That is it as far as the normal email client goes, but when you have to do the business yourself, you need to know a little more about how everything works.
To start with, you need to connect to the correct port. Usually, the standard port for POP communications is port 110. If you know that you Local Area Network uses a different port, then you will need to make sure that you set that when connecting.
For this article, I used the Winsock control to operate with. I will now give a few details about how the Winsock control operates.
The Winsock control does not provide us with many properties, but the ones we have, along with the methods and events make it a very powerful control. If you have read my previous article about the Winsock control (see Communicating over a network) then you will know how easy it is to connect two PCs together and send some data. In that example, we had to define a standard protocol for sending messages. First we sent the type of content, then the size and then the content. To communicate with a POP server, you need to understand the commands used.
A good way to learn about the commands is by downloading the trial version of MDaemon (http://www.mdaemon.com/) This is a very good mail server that allows you to see all the messages that are sent and received when it communicates with another server.
Anyway, let me explain how things work.
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