mailagent: 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/bin/mailagent - from package: mailagent

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

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