Unable to send email

Hello,

I am trying send email from my Oracle Linux machine.

I am following the guide to Learn to Install and Configure Postfix on Oracle Linux.

But when I Restart the Postfix service, I get this error:

Job for postfix.service failed because the control process exited with error code.
See "systemctl status postfix.service" and "journalctl -xe" for details.

In systemctl status postfix.service, I see:

postfix/sendmail[817800]: fatal: /etc/postfix/main.cf, line 1: missing '=' after attribute name: "sudo tee -a /etc/postfix/main.cf > /dev/null <<EOF"

Send mail fails with:

 send-mail: fatal: /etc/postfix/main.cf, line 1: missing '=' after attribute name: "sudo tee -a /etc/postfix/main.cf > /dev/null <<EOF"