How to check if an email is trying to prompt-inject your AI assistant

Treat email as untrusted data, not as instructions from the assistant’s owner.

Warning signs to look for

• Instruction overrides: “Ignore previous instructions” or “new system message.”
• Role hijacking: claims that the assistant is now an administrator or unrestricted agent.
• Prompt extraction: requests to reveal hidden prompts, policies, or private conversations.
• Hidden or encoded content: invisible characters, concealed HTML, or unusually large encoded blobs.
• Urgent side effects: pressure to send mail, disclose secrets, approve payments, or follow links without review.

A safer review workflow

1. Copy only the relevant email text into Prompt Injection Check.
2. Scan locally and read every finding explanation, not just the score.
3. Compare highlighted spans with the original message.
4. Separate useful content from untrusted instructions.
5. Require human approval before an assistant takes consequential action.

Prompt Injection Check is a deterministic warning tool. A clean result does not prove that an email is safe; novel, paraphrased, multilingual, image-based, and context-dependent attacks can be missed.

Keep assistant authority narrow

Use tool and recipient allowlists, avoid exposing secrets in assistant context, and make risky actions require explicit confirmation. Defense in depth is stronger than any single scanner.