I am setting up a Windows Server 2012 with IIS for PHP/Mysql-hosting. I soon as I start the SMTP-service (from IIS 6 Manager) the CPU-percentage in Task Manager spikes.
First when I got the server, I saw how it worked, and found out that spam-bots where relaying e-mails through the server. I set the SMTP-service to only allow connections through from localhost/server-ip. And so nothing shows up in the SMTP-service logs.
Could it be possible something is still hitting my server on Port 25, and it reaches the SMTP-service which denies access but still affects CPU? How can I troubleshoot this?
