How do you send mail from the mac terminal when nothing works?

I have tried dozens of different ways including using mail, mail, and sendmail. I've tried installing smtp, mstmp, postfix, sendmail. I really don't know what's going on, so internet people, can you help me?

Edit: When I type this command:

mail name@gmail.com

I get this error:

 unknown: fatal: /etc/postfix/main.cf, line 689: missing '=' after attribute name: "inet_interfaces loopback-only"

But if I try to edit that file in VIM it says its read only. In addition, I'm on a mac with a terminal running ZSH.