Thanks you for denyhosts!
My local SMTP does not listen TCP, unix domain socket is used. Can I use it for denyhosts?
I would be great to use mail (mailx) tool and pipe or some other external command because I will be able to configure my local server then.
MAIL_COMMAND=mail root --subject="ERROR $IP"
denyhost may then just write to stdin of this command.
https://github.com/denyhosts/denyhosts/pull/89