bf_copy: 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/bf_copy - from package: bogofilter

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

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