What does Email Authentication on your own server
When you send an email you need a SMTP outgoing mail server.
In most cases you would use your local ISP's SMTP server. This works well
while connecting through your local ISP, but when you go to a hotel or
guest house or at airports and restaurants with wifi nationally or internationally
you need to change to their server to be able to send emails.
With Email authentication on your own server you always
send email via your own server no matter what ISP you use or where you
are in the world.