reporter-mailx: 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 CentOS possible default full paths are:

/usr/bin/reporter-mailx - from package: libreport-plugin-mailx

You may install the required package with command yum install {package}

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