Write a function that automatically generates email for content moderation.

Given the inputs:

1. List of Detected Keywords: ["hack", "heroin"]
2. Keyword-to-Category Mapping: ["hack,Hacking", "heroin,Drug"]
3. Category-to-Instruction Mapping: ["Hacking, Please ensure that cheating mechanisms are reported promptly to administrators.", "Drug, Please be aware of drug dealing in the game, report to police if necessary."]

An example of how the output email body can look like:

Subject: Detected Keywords in the Game

Dear User,

Our system has detected the following types of activity in the game:

1. Hacking: Please ensure that cheating mechanisms are reported promptly to administrators.
2. Drug: Please be aware of drug dealing in the game, report to police if necessary.

We encourage you to remain vigilant and take the appropriate actions outlined above.

Best regards,
[Your Organization's Name]