Email Injection

I have feedback forms on several of my sites and recently, they have been plagued with email injection attacks.

The forms are pretty straight-forward. Half a dozen fields get submitted to a formhandler.asp page where the contents are sent to some hard-coded email addresses using ASPmail.

From what I understand about how this works, spambots are used to add carriage returns after some of the form fields and then adding BCCs in to use the form to send out spam to other addresses. Here's an example of the emails I'm getting: .....