Email and postal card

I read that sending an email is like to post a postal card. Your email passed from many servers to receive to the destination. I have a question, consider below local network:

One of the Desktop PC in that local network sent an email from his\her Gmail to other Gmail address. His\her email passed from the Desktop PC to the switch and then from that switch to the router then…
Is it true?

Thank you.

Hello! If someone were to use a gmail address, they’d be using google’s smtp servers, which means the email would first go to the google’s server through your isp, then processed in google’s server, then sent to its recipient through recipient’s isp. On the other hand if you were to deploy an smtp server on your local server, it’d only go through the switch and the router. (no internet).