qmqpfront-qmail: 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

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/sbin/qmqpfront-qmail - from package: mailfront

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