mailinspect: command not found

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/mailinspect - from package: dbacl

You may install the required package with command apt-get install {package}

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