Q:

SMTP networking at shared server

My website is hosted in a shared server. I would like to send an email from my website to my website's email address. (Using a shell script to be executed on the shared server.)
I am curious to know: Would the connection be channeled externally through the phone/dsl company or is it channeled internally by the server ?
If externally, how can it be done internally ?
telnet mail.mydomain.com 25
...
HELO mail.mydomain.com
...

A:

It would go through a "fake" loopback interface. i.e., it'd be taken through an internal path within the network stack. You can confirm by taking a packet trace through tcpdump or by looking at the headers in the delivered email.

