If you installed XAMPP you need to configure XAMPP`s mail module: Mercury Mail
Start the "XAMPP Control Panel" then start "Mercury" then press the "Admin" button:
Then "Configuration" and after that go to "MercuryS SMTP Server":
and to "Connection Control" where the "Do not permit SMTP relaying of non-local mail" is
MARKED
You must
UNMARK that !
After that you must delete the existing users from the mail module (Mercury Mail) and create your own one
(e-mail admin)