This question pops up some times, we say please use IMAP its a more modern protocol and fits much better with the way we are using email these days over multiple devices. 

IMAP PRO's
- IMAP leaves mail on the server with a local copy on your device
- IMAP can connect from several different devices and see your email (including if you read the mail already or not)
- IMAP folders are backed up if you backup your site too, so one backup contains everything.
- used by modern mail applications, smartphones and so on by default.

IMAP CON's
none, unless you dont trust to have your mails stored at the server of your mail/hosting provider.