Re: I need help with pf and smtpd.conf to deal with an ongoing attack on port 25 that is sending out emails.

Open Mail Relay: Why It Is Considered A Spammer's Dream
https://www.duocircle.com/content/mail-relay-smtp/open-mail-relay


An open mail relay is a Simple Mail Transfer Protocol (SMTP) server
configured in such a way that it allows anybody on the Internet to send
e-mail through it https://en.wikipedia.org/wiki/Open_mail_relay


An open relay is generally understood to be a server that allows emails
from any sender to any recipient without the need for authentication.
This represents a considerable risk because such servers are often used
by 3rd parties to send SPAM. https://www.ionos.co.uk/help/server-cloud-infrastructure....


Being a postmaster is a specialised job.

Welcome to the real world.


Configure your MTA properly or stop it sending and relay through your
ISP instead.