Introduction

OWAMailboxPolicy no longer needs to be set manually with Powershell commands as it is now part of the default OWA functionality. If you have set up this policy manually for your users, you should disable it to ensure users won’t encounter unexpected behavior when sending emails from the OWA.

Disable OWAMailboxPolicy

To disable OWAMailboxPolicy:

1. Connect to Exchange via PowerShell

   Import-Module ExchangeOnlineManagement
   Connect-ExchangeOnline -UserPrincipalName admin@domain.com
   

2. Check the available OwaMailboxPolicies and their value for OnSendAddinsEnabled. Make sure the default for this value is set to FALSE:
   Get-OwaMailboxPolicy | fl name, onsendaddinsenabled

3. Change the OwaMailboxPolicy for every user:
   Get-User -Filter {RecipientTypeDetails -eq 'UserMailbox'} -ResultSize Unlimited | Set-CASMailbox -OwaMailboxPolicy OWAMailboxPolicy-Default

4. Close the Connection to Exchange:
   Disconnect-ExchangeOnline

5. Cancel/delete the task to give new users the OwaMailboxPolicy

   1. Open the Windows Task Scheduler
   2. Search for the task that enables OwaMailboxPolicy
   3. Disable or delete the task