What is IMAP and what are its specific advantages over POP3?

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IMAP stands for "Internet Message Access protocol) - a email service which helps accessing your mailbox from different computers and locations. The IMAP service allows the user to download only the message headers and decide if they want to actually download the rest of the message and the attachments.

IMAP was designed to overcome some problems with POP behavior and provide more features for delivery and management of e-mail. With IMAP, mail is kept on the mail server and is managed there by a series of commands sent to the server by your client. Copies of messages and attachments are transferred to a email client only when one request them.

By default, only descriptive information about your messages is sent to your client. This works very well over slow links or for access from devices with limited computing or storage capacity such as a PDA, mobile phone or dialup internet access.

This feature makes downloading large attachments on a slow connection more manageable and efficient. In addition, the IMAP service provides folders for the user to store emails and attachments on the server so that they can retrieve those stored messages when they log into the server from different computers.

In practical areas where POP is weak, with respect to online/disconnected operation, are strengths for IMAP, since online access was its original design center. These new features provide powerful benefits that allows the user to create folders for received and sent messages to be retrieved from any computer.

The advantages of IMAP is that it is more feature-rich and allows you to read your e-mail from any location and any device with IMAP support.

Some specific advantages of IMAP over POP include:

• Robust folders for storing received and sent messages
• Freedom for user to download attachments at will
• Provision for determining message structure without downloading entire message.
• Selective fetching of individual MIME body parts.
• Server-based searching and selection to minimize data transfer.
• Ability to append messages to a remote folder.
• Ability to set standard and user-defined message status flags.
• Support for simultaneous update and update discovery in shared folders.
• New mail notification.
• Ability to manipulate remote folders other than INBOX.
• Remote folder management (list/create/delete/rename).
• Support for folder hierarchies.
• Suitable for accessing non-email data; e.g., NetNews, documents.
• In IMAP, when a client program performs any operation on a mailbox, the server will automatically include in its response notification of any new messages that have arrived since the last notification.
• IMAP's ability to manipulate remote folders other than INBOX is fundamental to online and disconnected operation. This means being able to save messages from one folder to a different one, being able to access archived messages subsequently, and allowing for multiple incoming message folders.