Sending Email Directly From A Mail Server Terminal, How To Manually Specify Source IP?

Trying to send an email to my gmail account via the command line.

I can issue the following command in terminal

mail -v -s "test" xxxxx@gmail.com -- -f ooooo@mydomain.com

The problem is, the server I'm on is not my domain's mail server, so emails keep ending up in the spambox.