qmqp-sink: 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/sbin/qmqp-sink - from package: postfix

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

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