POP
Best when you will be primarily accessing your email from a single location, like your office or home. When you leave your office or home, you can still access your email from a web browser.
Messages are downloaded to your computer, so you don’tneed to worry about exceeding the size of your mailbox.
When accessing your email account through a web browser, you may not see previous messages that were downloaded to your desktop email client.
IMAP
Best when you will be accessing your email from multiple locations.
Allows you to create portable folders. These folders will appear in each email client you use to access your account. Your account will look the same at work, at home, and at your friend’s house.
Because your email messages are stored on the server, you must monitor your mailbox size and delete messages to avoid exceeding your mailbox size.