If you are a system administrator and working in web hosting company. So it’s your responsibility to maintain server uptime. Sometimes issue come with mailserver. If you see in your mail queue on server you will see large number of mails in queue. Generally it happens in shared hosting. If you have vps or dedicated server so you can run below command on SSH windows after that you will see list of directory from where mails are sending and you can easily track spammer path.

grep cwd /var/log/exim_mainlog | grep -v /var/spool | awk -F"cwd=" '{print $2}' | awk '{print $1}' | sort | uniq -c | sort -n 

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