Hi Omran,
Sorry that my knowledge about custom IRM Protector is quite limited. But regarding your concern about whether Outlook supports IRM, I did some research and found that it is supported to restrict permission to content in email messages in Outlook with
Information Rights Management (IRM), just as you can restrict permission to other Microsoft Office files.
For more information, hopefully you can find the article below helpful:
Introduction to IRM for email messages
Hope you can find the above information helpful.
Best regards,
Yuki Sun
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