They use my Exim. How to prevent it?

Question

Exim

Hello.
I have a mail server for my needs.
But I often receive messages from PS with such content Report Domain: my domain.ru Submitter: yahoo.com Report-ID: <1444528122.238737>
These are their mini mailing reports.
Although I don't post.
Means someone uses my exim.
How to prevent it?
Through putty, I look at what and how is now with my server through the commands on this page ( vds-admin.ru/mail/poleznye-komandy-pochtovogo-serv...
there are always other people's addresses to which I do not send mail.
What to do like this prevent.Except
for stopping the mail server?

Answer 1

Not at all, just a report comes to you about how many letters were sent to a particular mailer.
you can turn it off by setting p=reject in the DMARC settings;

Answer 2

Try checking the server on open relay https://mxtoolbox.com/diagnostic.aspx.
Then look in the settings for trusted networks, enable SMTP authorization ..

Answer 3

If they pour on behalf of other people's domains, then - https://debian.pro/1541
Then look for who sends. Most likely, they broke some site and pull the script that is sent through the mail () function from php (it can be logged separately).