Exim4, grep the log files
From Andreida
IPs with failed login
List all IPs whit a failed login and give a count of how often they tried (maxed by deleted old log files)
zgrep -o 'failed for (\[.*\])' /var/log/exim4/rejectlog.* | grep -o '\[.*\]' | sed 's/^.//' | sed 's/.$//' | sort | uniq -c | sort -n