An email program, called an email "client" is used to retrieve mail from a computer on the internet and to send mail from a computer on the internet. Computers on the internet are usually called "servers".

It is important to note that the computer used for handling your email can be quite separate from the computer which you use to log onto the internet.

In fact, you can log on to one system (say IBM.NET or Sympatico.ca or @Home) and get email from as many different computers as you wish. e.g. when you "dial up" a computer, you are NOT necessarily calling your email computer. The computer handling your email is accessed by addressing it (from the internet once you are connected) using an internet address such as @name.com or its numerical equivalent.

Many ISPs (Internet service providers like AOL, Compuserve, IBM, etc) do not allow you to "relay" mail - i.e. to send out email through another server (because of email abuse problems). Therefore, you will find yourself sending and receiving email through entirely different servers.

For example, if you dial up and connect via IBM.NET, you will have to send all your email via the IBM email server but you can certainly retrieve your email from any other email server on the net.

For receiving your email, a protocol referred to as POP (Post Office Protocol) is used to download your new mail from remote your mailbox over the internet.

POP or POP3 "host" is the name of the machine from which your email "client" program should retrieve your new mail. Usually it is just the internet address for the computer which is handling your email. It might be a name like popserver.sfu.ca or an address like 123.321.123.321. To access a POP host, you need to supply the host's name, your username, and your password.

For sending email, a protocol referred to as SMTP (Simple Mail Transfer Protocol) is used. Even if you use many different email IDs, you will likely always use the same SMTP setup for sending mail, although your POP setups will vary (due to the relay problem mentioned above). So, when you log onto IBM.NET, for example, only the IBM SMTP server for email will allow you to send email - because IBM will not permit relaying.

This all sounds simple enough, but there's one more important point to note: When your recipients receive their email, there is a "header" in the message which tells them who it is from so that you (or your computer can do it automatically) can "reply" to the email. In your email client, you can generally set the "From" address to almost anything you want. If you make a typo, you won't get your email.

So, if you are using different email servers for different purposes, you have to be careful to change (or use different copies of the email program) your "From" field when sending (to avoid confusion among your correspondents) and you have to be careful to change your POP settings for each of your email accounts.

Final word - not all email clients work the same - this may drive you crazy. It has already done so for me!

Mike Volker