mailping-cron: 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/mailping-cron - from package: mailping

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

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