Today, my mail server had its first-ever spambot attack. On my normally quiet system, over 2500 messages from over 1200 unique IP addresses were greylisted, and over 650 messages from more than 550 unique IP addresses made it through my greylist and were caught sending spam to invalid addresses on my system.

This graph shows the effects on my otherwise quiet server:

I ended up writing a little bit of code that trapped these and added them to the dynamic blacklist on my firewall. It was a fun little bit of perl coding, but took far too much time away from my study day.