The Difference Between POP3 and IMAP

There are two different protocols available to access e-mail: POP3 and IMAP.  POP3 is useful when e-mail is checked from only one computer.  IMAP is the better choice when you would like to check your mail from multiple computers, at work and home, for example. IMAP has the added benefit of accessing folders on the server, allowing you to organize your e-mail, and access it from anywhere.  Tulane's Webmail uses IMAP. If you use Webmail, you should use IMAP on all of your e-mail clients. Use of a POP3 mail client in association with Webmail can cause errors in your inbox that will result in a temporary loss of access to your mail.

- The Difference
- Scenarios of Use
- Tips
- Errors caused by using POP3 and Webmail

The Difference

POP3 works by reviewing the inbox on the mail server, and downloading the new messages to your computer.  IMAP downloads the headers of the new messages on the server, then retrieves the message you want to read when you click on it. 

When using POP3, your mail is stored on your PC. When using IMAP, the mail is stored on the mail server. Unless you copy a message to a "Local Folder" the messages are never copied to your PC.

Scenarios of Use

POP3

• You only check e-mail from one computer.

• You want to remove your e-mail from the mail server.

IMAP

• You check e-mail from multiple locations.

• You use Webmail.

Tips

Keep your Inbox small! This will speed up your e-mail retrieval.  Checking the e-mail is directly dependent on how many e-mail messages are in your inbox on the mail server.

POP3

• Set to remove mail from server after 30 days.

• Don't check more frequently than every 15 minutes.

• POP'ing large mail boxes consumes excessive server resources.

IMAP

• Do NOT check all folders for new messages! This slows your e-mail substantially.

• You can set your client to download the mail and to remove the mail from the server, like a POP3 client.

• Organize your mail into folders, and archive your older messages.  This speeds e-mail retrieval by minimizing the number of messages in the inbox.

Errors caused by using POP3 and Webmail

When used in conjunction with a permanent e-mail client, Webmail can be a useful way to check and send messages while you are away from your computer. However, if there is a POP3 e-mail client automatically checking your mail every so many minutes, and you are also accessing Webmail from another location, there is the possibility that your mailbox will be empty in Webmail. If you plan on using your webmail make sure there is no other POP3 clients open so you can receive your email in the webmail interface.


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