Microsoft Defender for Office 365 Blocks Prompt Injections

Microsoft Defender for Office 365 (MDO) can detect and quarantine email containing prompt injections. Shared mailboxes might need MDO Plan 2 licenses if they receive email from external domains. This requirement existed before MDO introduced Prompt Injection Protection, but the advent of the new capability is another reason to check mailbox licensing, especially if your tenant uses Copilot. We have a script to help!

https://office365itpros.com/2026/08/04/microsoft-defender-prompt-injection/