POP3 and IMAP are two different protocols (methods) used to access email.
POP3
POP3 is short for Post Office Protocol.
POP3 downloads email from a server to a single computer, then deletes it from the server. Because your messages get downloaded to a single computer or device and then deleted from the server, it can appear that mail is missing or disappearing from your Inbox if you try to check your mail from a different computer.
Pro’s: POP3 is useful if you have a single device that you check email from.
Cons: If you check emails from multiple devices you’ll lose email addresses as some will be on one device and others on another. There is no consistency.
IMAP
IMAP is short for Internet Message Access Protocol.
IMAP keeps your email on the server and allows you to check your emails from multiple devices, such as a work laptop, a home computer, or a tablet, smartphone, or other mobile device. IMAP allows you to use server side filtering if needed into folders.
