Tried to upgrade mutt, then followed the instructions to sudo and set the appropriate files (chgrp said they weren’t there), so did a brew reinstall mutt, that worked and files were present.
Tried to run and it wouldn’t load with
dyld: Library not loaded: /usr/local/opt/libidn/lib/libidn.12.dylib
Referenced from: /usr/local/bin/mutt
Reason: image not found
Abort trap: 6
Then did brew install libidn and it worked