spfd: 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 CentOS possible default full paths are:

/usr/share/doc/perl-Mail-SPF-2.8.0/sbin/spfd - from package: perl-Mail-SPF

You may install the required package with command yum install {package}

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