withlist: 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/withlist - 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/withlist - from package: mailman
/usr/sbin/withlist - from package: mailman

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

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