When it comes to checking your mail, unless you want to use a web-based interface, you will need to use your mail client to connect to your mail server to download your messages. There are two protocols for accomplishing this, POP and IMAP. POP is what I had always used since the first time I ever set up an email account. It was simple, everyone else used it, and it worked; so I never really thought about trying anything else. I now realize that I could have saved myself a lot of trouble over the past 10 years if I had learned about the strengths of IMAP long ago.

POP is a very simple protocol. There is one mailbox, and there are two operations that you can perform on messages in it: Download and Erase. This is quite adequate when you have only one machine--because all you need to do is just download all of your mail and clear the messages off the server.

However, if you use multiple machines to check your email, then the problem becomes much more sticky. In such a case, you don't want to clear the server of all messages each time one of your machines checks your mail, because then that email would only be available to be read on one machine. The solution is to set each machine to not clear the messages off of the server immediately, but only erase messages that are older than a certain period(say, a week). For the longest time, I thought this was the only solution.

With POP all mailboxes and mail folders are all stored client side, which means that they can have different contents on each machine you use depending on how often you check your mail on each machine. Cleaning out your inbox on one machine does nothing to clean out the inboxes of the other machines, even though it is still conceptually the same inbox. IMAP works considerably differently, as it allows you to keep and manage your mail inbox and other mail folders server side.

Suddenly, all of my email clients are in sync. When I have mail, all of my machines will show it--but I only have to read that email on one of my machines for the "new mail" condition to be re-set. The next time the machine checks my mail, it will notice that I have read the email and no longer mark it as read.

This suddenly opens up new possibilities that I had discounted before. For example, my cell phone has the ability to check my email. However, I had largely ignored this feature because my phone had no reasonable way to filter out spam. With IMAP, I now use SpamAssassin to sort all of the junk mail into its own spam folder server-side. This allows my cell phone to actually check my mail in a useful fashion without being inundated with junk.

Anyway, if you use an email program such as Outlook Express, Mozilla Thunderbird, or Apple Mail to check your mail and your server supports IMAP, I highly recommend using it if you use multiple machines. It is a superior protocol to POP. Don't waste a decade like I did.

Don't forget to enable SSL encryption if your server supports it!

Links

• The IMAP Connection
• SpamAssassin