nmzmail: 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
/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/bin/nmzmail - from package: nmzmail

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