spamd: 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/bin/spamd - from package: spamassassin

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

On Debian possible default full paths are:

/usr/sbin/spamd - from package: spamassassin

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

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