maillist: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/maillist - from package: mailagent

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