policyd-spf: 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/policyd-spf - from package: postfix-policyd-spf-python

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

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