Secure authentication for Postfix & Dovecot

[minhnghivn]

Using Thunderbird as mail client, I notice an option in the mail account's Server Settings which reads "Use secure authentication" which allow secured transition of your username and password.

I also have my own mail server. Hence, how do I enable this functionality for my mail server (I'm using Postfix & Dovecot) ?

Any help will be highly appreciated