Reporting possible EC2 abuse

Hello,

How do I report spam-related activity on EC2?

The pattern of the perpetrator:

• orders an EC2 instance
• sends spam messages from it for 2-3 days
• rebuilds instance (to get a different IP)

Email in question has no valid authentication (SPF, DKIM etc), so spam filters kill it on entrance, but I'd prefer to get more permanent solution for that.