I am running CentOS and several times see "SASL LOGIN authentication failed: authentication failure". Seems someone is trying to logon to my mail server illegally.
I have installed fail2ban to block such cases automatically. But I want to test that by simulating this situation. I created an account in my thunderbird mail client and provided wrong credentials to my server but this doesn't generate anything in my server's maillog.
Can someone please suggest me how can I produce "SASL LOGIN authentication failed: authentication failure" ?