Postfix/mail server security with duo?


Very new here to duo, so apologies if this is answered elsewhere.

We would like to add security to our unix server for direct access (ssh), web access and email. I have already set things up for ssh and have some confidence that there is a path forward for web pages, but am unclear on how to proceed for our postfix email server. It would be nice if MUAs connecting via imap/pop would periodically (daily?) require a duo checkin. Looking at this site I’m wondering if something similar could be done using an imap proxy server: