spamprobe: 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/spamprobe - from package: spamprobe

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

On Debian possible default full paths are:

/usr/bin/spamprobe - from package: spamprobe

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

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