rmlist: 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/lib/mailman/bin/rmlist - from package: mailman

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

On Debian possible default full paths are:

/usr/lib/mailman/bin/rmlist - from package: mailman
/usr/sbin/rmlist - from package: mailman

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

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