mlmmj-maintd: 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/mlmmj-maintd - from package: mlmmj

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

On Debian possible default full paths are:

/usr/bin/mlmmj-maintd - from package: mlmmj

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

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