Question
What is the difference between IMAP and POP3?
Answer
When you use POP3, the mail server deletes messages from the server when downloaded. That means that messages can only be accessed from the computer to which they were downloaded.
When you use IMAP, the mail server stores messages on the server until the user deletes them. This means that messages can be accessed through any computer. Also, unless you use a mail client that synchronizes folders and caches messages, IMAP requires a constant connection while you read messages.