warning to #neomutt users upgrading to #debian #Bullseye: the "mutt" package became "neomutt" & the original #mutt took on the pkg name "mutt". So if you inadvertently install mutt, you'll run into problems like mutt using the variable smime_self_encrypt while neomutt names it smime_encrypt_self. And /usr/share/doc/muut/NEWS.Debian does not mention this.