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Outlook Encrypted Email Issues
I have deployed M365DLP controls to block password protected atachments that cannot be scanned and am telling users to use Outlook Encryption instead to protect outgoing email attachments. However,...
Hi GrahamP67,
First all the error code AADSTS90072:
"...The external account that the user signs in with doesn't exist on the tenant that they signed into; so the user can't satisfy the MFA requirements for the tenant... The account must be added as an external user in the tenant first"
https://learn.microsoft.com/en-us/azure/active-directory/develop/reference-error-codes
Emails can only be opened in the Outlook Desktop App when the recipients are added as Azure guests to your tenant. This is by design. Please note that the behavior possibly is different in the Outlook Mobile App or in Outlook on the web.You might also need to exclude "Microsoft Azure Information Protection" cloud app from CA policies that enforce multifactor authentication on your tenant.
