setmaillist: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/bin/setmaillist - from package: fastforward
/var/lib/qmail/bin/setmaillist - from package: fastforward

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