sendmail2snpp: 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 Debian possible default full paths are:

/usr/bin/sendmail2snpp - from package: sendpage-client

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

Error in other languages:
sendmail2snpp: bevel nie gevind nie
sendmail2snpp: comandă negăsită
sendmail2snpp: comando não encontrado
sendmail2snpp: commande introuvable
sendmail2snpp: command not found
sendmail2snpp: käsku ei ole
sendmail2snpp: không tìm thấy lệnh
sendmail2snpp: komanda nerasta
sendmail2snpp: Kommando nicht gefunden.
sendmail2snpp: kommandot finns inte
sendmail2snpp: komut yok
sendmail2snpp: nie znaleziono polecenia
sendmail2snpp: níor aimsíodh an t-ordú
sendmail2snpp: no se encontró la orden
sendmail2snpp: no s'ha trobat l'ordre
sendmail2snpp: opdracht niet gevonden
sendmail2snpp: parancs nem található
sendmail2snpp: perintah tidak ditemukan
sendmail2snpp: príkaz nenájdený
sendmail2snpp: příkaz nenalezen
sendmail2snpp: команда не найдена
sendmail2snpp: командата не е открита
sendmail2snpp: 命令找不到
sendmail2snpp: コマンドが見つかりません