Incoming mail server types: POP3 vs IMAP Configuration
There are two protocols associates with email coming into your email software. POP3 used to be the preferred protocol when connecting to your incoming mail server when users didn't have multiple devices, and server storage could potentially play as an issue. Recently IMAP becomes the more popular protocol, and this especially holds true for users with multiple devices.
The POP3 protocol or "Post Office Protocol" functions very similar in nature to that of your local post office. Imagine picking up your everyday mail from a post office box every day, on your way home from work/school. you walk into the post office, put your key in the PO Box to open the door, then remove the mail from the box. Last but not least you close and lock the door of the PO Box again. You then finally get home to read your mail. Generally whatever mail we didn't want would be thrown away never to be seen again. This is exactly how the POP3 Protocol works. Once is collects all of the emails from the mail server, all of that email is stored locally in your computer's email client (ex. Microsoft Outlook, Mozilla Thunderbird, or Apple Mail). This configuration is generally offered if the user only looks at email on one device, or if the storage size of the mailbox is not capable of holding a lot of emails.