sup-psych-ify-config-files: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/sup-psych-ify-config-files - from package: sup-mail

You may install the required package with command apt-get install {package}
Error in other languages:
sup-psych-ify-config-files: bevel nie gevind nie
sup-psych-ify-config-files: comandă negăsită
sup-psych-ify-config-files: comando não encontrado
sup-psych-ify-config-files: commande introuvable
sup-psych-ify-config-files: command not found
sup-psych-ify-config-files: käsku ei ole
sup-psych-ify-config-files: không tìm thấy lệnh
sup-psych-ify-config-files: komanda nerasta
sup-psych-ify-config-files: Kommando nicht gefunden.
sup-psych-ify-config-files: kommandot finns inte
sup-psych-ify-config-files: komut yok
sup-psych-ify-config-files: nie znaleziono polecenia
sup-psych-ify-config-files: níor aimsíodh an t-ordú
sup-psych-ify-config-files: no se encontró la orden
sup-psych-ify-config-files: no s'ha trobat l'ordre
sup-psych-ify-config-files: opdracht niet gevonden
sup-psych-ify-config-files: parancs nem található
sup-psych-ify-config-files: perintah tidak ditemukan
sup-psych-ify-config-files: príkaz nenájdený
sup-psych-ify-config-files: příkaz nenalezen
sup-psych-ify-config-files: команда не найдена
sup-psych-ify-config-files: командата не е открита
sup-psych-ify-config-files: 命令找不到
sup-psych-ify-config-files: コマンドが見つかりません