snsend: 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/sbin/snsend - from package: sn

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