IMAP works differently than POP, as it does full synchronization of emails. While you might think this is a problem, most believe it to be much more robust than POP, as long as all of your devices you use are using the IMAP protocol then every client will contain the same contents, which is something POP could not do. If there is such an option it would be in your mail client, but like I said just switch them to use IMAP everywhere and you should be good to go, even if they login to their webmail they will have a uniform experience.