I am running macOS Catalina on a late 2013 iMac and I use MacPorts for installing various command line tools. Although I do use the Mac Mail app a bit I still handle most of my email using Mutt, or rather the fork called NeoMutt. I also want the ability to send and receive signed and encrypted emails using GnuPG. So my two most important ports are probably neomutt and gnupg2. I also use GnuPG to encrypt files using a symmetric cipher, in particular a file containing all my passwords.