IMAP (Internet Message Access Protocol) 比先前的 POP3 電子郵件協定先進，IMAP 功能較強，更能符合「收信」的需求‧ (IMAP) is far more comprehensive and capable than the previous POP3 email standard. It enables many of the advanced features described in these pages, including webmail, multiple mailboxes, nested folders, and blazing-fast search to find that message you know is in there somewhere. With IMAP, you manage mail directly on your provider's server via a web browser. This server-based approach delivers a number of powerful advantages, a handful of which are listed below.

• scan just the headers

When you're in a hurry (like when are you not?), view headers only to quickly locate and read time-critical messages first.

• minimal downloading

save only messages you wish to store or edit locally. All other mail can be read, responded to, forwarded or deleted directly on the web. This is an even greater plus when you're using a cell phone or PDA to access your mail.

• flag critical messages

Mark messages as read, forwarded, replied to, or critical. Pull up messages requiring immediate attention with a single mouse click.

• share mailboxes with colleagues

Optionally set up common mailboxes with trusted partners so all can see incoming communications simultaneously without forwarding lag time.

• no need to synchronize

because you can leave messages on the server, it isn't necessary to "synchronize" desktop, laptop, cell phone, or other devices accessing your centralized mail storage.

IMAP enables the advanced mailbox and folder operations further described on the following pages. Also, because it was designed (initially at Stanford University) as a superset of the POP3 standard, IMAP supports all the common features you've become accustomed to, such as cc and bcc fields, forwarding to remote accounts, sending and receiving attachments, and HTML mail.