通过电子邮件前端防止垃圾邮件

I've written a bug reporter for my game, and after it launches, the user can review the data and submit the report to my web server via HTTP. If the submission fails, the user has the option to save the report and try again later, using the bug reporter itself, uploading the file with a web form, or attaching the report to an e-mail. I know that I can prevent spam over HTTP by analyzing the source IP, but I'm not sure how to go about this when receiving reports over e-mail. Any ideas?I've written a bug reporter for my game, and af