mbpath: 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/lib/cyrus/bin/mbpath - from package: cyrus-common

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

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