What is the difference between POP3 and IMAP?
It is common when bringing in e-mail with POP that you pick up the mails all from the server and store them on your PC. Once this is done, the e-mails are deleted from the server. Sometimes immediately but often after, say, 1 or 2 weeks.
Using POP3 is fine if you don't need to share mail with several people on different devices. One problem with using it may be that it only pulls in the "inbox" folder and not the spam folder. You may then start missing e-mails that ended up in the spam folder, rightly or wrongly. To see these, you would then have to log in to this mailbox using webmail to still be able to see them.
If you do want multiple people to read the mail, it may be more convenient to use the IMAP protocol where the mail remains on the server. That way, multiple people or devices can look at the same mail because it is not deleted from the server after reading it. This happens only when the mail is explicitly deleted from the server.
Another advantage is that you do get to see all folders like the spam folder or sometimes the junk folder.