Using POP3, the client software will download all unread mails to the computer, and the mail server will delete the mails.

Use JIMAP; the client software will download all unread mails to the computer, and the mail server will delete the mails.

With IMAP, users can directly operate on the mail on the server, without downloading all the mails locally to perform various operations.

Using POP3, users can directly operate on the mail on the server without sending all mails to the local to perform various operations.