mboximporter: 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/mboximporter - from package: kmail

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