masqmail: 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/masqmail - from package: masqmail

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

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