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"We can't display your message right now" error in Outlook Web App when an Exchange Online user views an encrypted message

  • 05/05/2025
  • Applies to: Exchange Online

Original KB number: 2971787

Problem

When a Microsoft Exchange Online user tries to read a message that was encrypted by Microsoft Purview Message Encryption in Microsoft Outlook Web App, the user receives the following error message: We can't display your message right now. This issue occurs even if the user can send encrypted messages from Outlook Web App.

Cause

This problem occurs because the MIME types that are associated with the default Outlook Web App policy changed so that the text/html MIME type was removed or changed.

Solution

To resolve this problem, reset the MIME types that are associated with the default Outlook Web App policy to the default values. To do this, follow these steps:

  1. Connect to Exchange Online by using remote PowerShell. For more information about how to do this, see Connect to Exchange Online Using Remote PowerShell.

  2. Run the following commands:

    $owapolicy = Get-OwaMailboxPolicy

    Set-OwaMailboxPolicy -AllowedMimeTypes @{remove = "text/html"} -BlockedMimeTypes @{remove = "text/html"} -ForceSaveMimeTypes @{add = "text/html"} -Identity $owapolicy.Identity

    Note

    It may take as long as 30 minutes for the changes to take effect.

More information

For more information about Outlook Web App mailbox policies, go to Outlook Web App Mailbox Policy Procedures.

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