It's not needed, but not using SSL or STARTTLS on those protocols would allow clear text authentication. In 2020 this shouldn't be allowed at all.
Authentification should only be allowed if the client is using SSL port of these protocols and/or STARTTLS !
Anyone could easily sniff passwords if you're accessing your mailboxes with these protocols on a compromisd public network ....
Sébastien Riccio
System & Network Admin
https://swisscenter.com