All Customers - POP or IMAP?
IMAP does not actually move messages onto your computer. You can think of an e-mail program using IMAP as a window to your messages on the server. Although the messages appear on your computer while you work with them, they remain on the central mail server. The Drawback to IMAP is that messages are not downloaded to your computer, so over time you will run out of space on the mail server if you do not manage your email well.
POP does the opposite. Instead of just showing you what is in your inbox on the central mail server, it checks the server for new messages, downloads all the new messages in your inbox onto your computer, and then deletes them from the server. This means that every time you use POP to view your new messages, they are no longer on the central mail server.