How to disable Sendmail

1. Open /etc/rc.conf:

    $ ee /etc/rc.conf
   

2. Edit/Add these options:

    # NO SENDMAIL
    sendmail_enable="NO"
    sendmail_submit_enable="NO"
    sendmail_outbound_enable="NO"
    sendmail_msp_queue_enable="NO"
   

   Note: on old fbsd versions, it was used “NONE” instead of “NO” for sendmail_enable

3. Stop the sendmail service:

    service sendmail stop
   

The main reason why someone would disable the sendmail service are usually:

1. If you’re using a crappy vps, it will take some hard disk usage.
2. For better alternatives
3. For minimal OSes

By default sendmail should work only locally.