postfwd2: 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/postfwd2 - from package: postfwd

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

Error in other languages:
postfwd2: bevel nie gevind nie
postfwd2: comandă negăsită
postfwd2: comando não encontrado
postfwd2: commande introuvable
postfwd2: command not found
postfwd2: käsku ei ole
postfwd2: không tìm thấy lệnh
postfwd2: komanda nerasta
postfwd2: Kommando nicht gefunden.
postfwd2: kommandot finns inte
postfwd2: komut yok
postfwd2: nie znaleziono polecenia
postfwd2: níor aimsíodh an t-ordú
postfwd2: no se encontró la orden
postfwd2: no s'ha trobat l'ordre
postfwd2: opdracht niet gevonden
postfwd2: parancs nem található
postfwd2: perintah tidak ditemukan
postfwd2: príkaz nenájdený
postfwd2: příkaz nenalezen
postfwd2: команда не найдена
postfwd2: командата не е открита
postfwd2: 命令找不到
postfwd2: コマンドが見つかりません