You can find out the details spammers from mail queue itself. you can check it by using following commends :
This commands shows the total number of mails in the queue.
To check details ID,sender,Recipient,size and age of mail Run following commends :
By using the ID we can find the header,body and the log of message.
exim -Mvh ID
Also you can check by using “ConfigServer Mail Queues” if you running cPanel.