esmtp-wrapper: 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/esmtp-wrapper - from package: esmtp

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

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