mlmmj-receive: 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-receive - from package: mlmmj

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

On Debian possible default full paths are:

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

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

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