authenumerate: 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 Debian possible default full paths are:

/usr/sbin/authenumerate - from package: courier-authlib

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

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