IMAP vs. POP

Apple's Mail program can handle three types of incoming mail "protocol": IMAP and POP (or POP3, to be specific), and Exchange. A protocol is a particular set of standards having to do with communications between computers. You can set up IMAP or POP accounts in Mail; see the following pages.

POP3 (Post Office Protocol 3) is a protocol in which the server automatically downloads the mail to your computer when you check mail, then deletes the mail from the server. With POP you cannot read mail until it has been downloaded to your computer. POP works best for users who always use one computer on which the email files are stored and managed.

Email from a POP account is stored "locally," which means on your hard disk.

You can choose to leave your mail on the POP server after it has been downloaded to your Mac (see page 441), but check with your service provider before you do thatit might annoy them to have all of your email clogging up space on their server.

IMAP (Internet Message Access Protocol) is a protocol that receives and holds email on a server for a certain amount of time, typically thirty days. IMAP allows you to view email before deciding whether or not to download it to your computer.

Email from an IMAP account is stored on a remote server (although you can keep copies on your hard disk).

One advantage of IMAP is that you can manage your email from multiple computers because the email files are kept on the IMAP server for storage and manipulation; this means you can check your mail on a computer while you're on holiday in Istanbul, and when you come home, you'll still have the same messages available at home that you read in Istanbul.

Another advantage is that you can choose not to download emails that have large attachments or email from people you don't want to hear from. You can wait until it's convenient, until you know who an attachment is from, or you can just delete unwanted or unsolicited email and attachments before they ever get to your computer.

When you sign up for a Mac.com email service through .Mac, you're assigned a 125-megabyte mailbox on Apple's IMAP mail server. All unread messages within an account, even deleted messages, are stored on Apple's server. If you have more than 125 megabytes of mail and attachments, people will not be able to send you any more email at that account until you clear it out. See Section 2 for more information about .Mac accounts.

Exchange is an option for you if your company uses the Microsoft Exchange server and your administrator has configured it for IMAP access. You'll have to talk to your system administrator for details on setting this up!