openchange_newuser: 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/sbin/openchange_newuser - from package: openchangeserver

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

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