Howdy, I found 1 unanswered topic similar to mine.
Is it possible to DNS blacklist single or entire octets of IPV4 address space in particular APNIC that is generally nothing good from that part of the world.
Nothing in the doco about Fail2ban.
My mail log sustains for days on end the following:
lost connection after AUTH from unknown [xxx.xxx.xxx.xxx]
My server doesn’t need this traffic.