spfd.mail-spf-perl: 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/spfd.mail-spf-perl - from package: spf-tools-perl

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