send-nntp: 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/lib/news/bin/send-nntp - from package: inn2
/usr/lib/news/bin/send-nntp - from package: inn

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

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