IMAP and POP are not interchangeable. POP works by contacting your email server and downloading all of your new messages from it. Once they are downloaded, they disappear from the server. If you decide to check your emails from a different device, the messages that have been downloaded previously will not be available to you. POP works fine for those who generally only check their email messages from one device; those who travel or need to access their email from various devices are much better off with IMAP-based service.
Unlike POP, IMAP allows you to access, organise, read and sort your email messages without having to download them first. As a result IMAP is very fast and efficient. The server also keeps a record of all of the messages that you send, allowing you to access the files you sent from anywhere. IMAP does not move message from the server to your computer; instead, it synchronizes the email that’s on your computer with the email that’s on the server.
IMAP allows you to access your email messages from anywhere, via as many different devices as you want. It only downloads a message when you click on it. Attachments are not automatically downloaded with IMAP making email messages load much faster. The last advantage is that IMAP can be used offline just like POP – you can basically enjoy the benefits of both protocols in one.