Using Classic Outlook on Windows for personal email, calendar, and contact management
Hello SH_,
Thanks for update. Seems in your case should be because of some transport rule policy automatically applied on your mails and as result it’s sending again with encryption. In that case, you need to contact your Microsoft365 global admin to check further because admin have permission to check this details from admin center. We appreciate your kind co-operation for the same.
Thank you so much for your precious time. Stay safe and healthy.
Regards,
Ankita Vaidya