Sensitivity Labels: "Too many users" error when adding many recipients to encrypted email

By Ashwin Venugopal -

 






Symptoms

You apply one of the following options to an email message by using a sensitivity label or email encryption in Outlook:
  1. Do Not Forward
  2. Encrypt-Only 
When you try to send this encrypted email message to many recipients, you receive the following error message:

Too many users have been granted access to this protected content. Reduce the number of users or replace users with user groups, and try again. 

Note:
  • The number of recipients that causes this error varies, depending on both the number of recipients and the length of each recipient's email address. For typical email addresses, this error usually occurs if hundreds of email addresses are added to the message.

  • Only the number of email addresses that are individually added to the recipient list causes this error.

Cause

This problem arises from the size restriction of the protection policy applied to the email. In Microsoft Purview Information Protection, this rigid size cap is set at 4 MB. The protection policy contains the permissions assigned to each recipient who is permitted to access the email message. If you include too many recipients, the size of the protection policy could surpass the 4 MB limit and trigger the error. 

Workaround

To work around this issue, try one of the following options:
  • Reduce the number of recipients or send the email message to each recipient individually. 
  • Send the email message to distribution lists or groups that contain the recipients.
  • If the recipients are within your organization, use a sensitivity label that has a different policy that grants permissions to all the desired users. For example- a label that uses administrator-defined permissions (such as the All Employees label) doesn't cause this error. 
Note- You must have the administrator permission to configure the sensitivity label. 

Conclusion

The error that occurred after adding many recipients for an encrypted email is resolved.

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