mmarch: 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/mmarch - from package: mailman

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

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