How to get rid of constant attempts to connect to Exim?

Question

linux

good afternoon comrades! I got the server on rhel on which the mail spins exim dovecot mysql. there are a lot of records in the logs of eksim about answered connections, spam is also sent from some accounts, although the password has been changed on them, and there is a suspicion that we are being used as a relay. I once encountered this problem and even solved it, but I can not remember how. please tell me where to start and where to dig to solve these problems

Answer 1

Fail2ban

Answer 2

thanks for the tips, in the end I persuaded the arrogance to rework the entire infrastructure, since there is little to redo, otherwise the server is running RHEL 5, and it is already very old