innmail: 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/innmail - from package: inn2

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

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