WESS Logo
seperator
Home | Client Info
seperator
POP3 vs IMAP

POP3

POP3 (Post Office Protocol v3) is the traditional way to access email. Email is delivered to the mail server, where it sits and waits for you to retrieve it, a process generally called store-and-forward. When you connect, your mail client downloads all new mail and then removes it from the server. Thus, you have exactly one copy of your mail, and it is on the machine currently running your email client.

Well, that's all well and good, but what if you have a laptop and a desktop, and you want to be able to access the same email on both machines -- for example, when you take your laptop on the road? There are options in your email client to enable features like this:

  • "Leave a copy of messages on server" causes your client to download all new mail, but NOT remove it from the server. Each mail client keeps track of what it considers to be "new" mail vs. mail that has already been downloaded. Occasionally, however, one or more of your email clients will become confused for some reason, and you will end up with duplicate copies of all the messages in your inbox.
  • "Delete messages from server older than XX days" causes your client to automatically remove all messages currently on the server that are older than a specified number of days. This lets you maximize your usability across multiple computers while minimizing your risk of downloading duplicate messages.
  • "Delete from server when deleting locally" causes your client to remove messages from the server that you delete after downloading them. This is good for unwanted messages -- you won't have to delete them again from your other computer(s) -- but you can't delete mail locally that you want to download on the other computer(s). If you've already downloaded the message, it won't be deleted from the other computer(s) local storage.

IMAP

IMAP (Internet Message Access Protocol) takes a completely different track than POP3, and in doing so solves many of the above issues. Email is still delivered to the mail server, where it awaits your arrival with baited breath. When you connect with IMAP, however, your messages are not removed from the server -- your mail client merely opens messages on the server. Most IMAP clients, by default, don't even download the whole message right away -- they just pull down the headers so you can see the date, from, to, subject line and size. If you want to download and view the message, the client will transparently do that for you when you click on the message.

Since the messages are never removed from the server, this means that all you need to do is configure the email client on another computer to use IMAP as well, and you can view all your messages from anywhere, anytime, without fear of losing messages or having duplicates.

When you do decide to delete messages, generally they are merely 'marked' for deletion -- in Outlook Express they appear with a line through them -- and do not actually get removed until you 'purge' the folder. Many other options are available.

The only potential issues with IMAP deal with specific email clients -- some are simply better at it than others. Most clients, however, do a good enough job to be usable, with positive results.

For more information about these topics, feel free to ask your friendly neighborhood WESS employee!