How to disable the Outlook Web App Sync feature

Scenario

You have migrated to use the Exclaimer Outlook Add-in and now you wish to stop the previous Outlook Web App (OWA) signatures from appearing when you compose your email.

Resolution

To disable the current Outlook Web App sync service, you need to:

Remove the Azure application

Delete all signatures from your end-users mailboxes

Removing Azure application

To remove the Exclaimer Azure app, please follow the steps below:

1. Log in to the Azure portal (https://portal.azure.com) as a Global Administrator.
   
   
2. Navigate to Azure Active Directory > Enterprise applications:
   
   
   
   
3. From the left-hand pane, under Manage, click All Applications.
   
   
4. Select Exclaimer Signatures for Office 365 Outlook Web:
   
   
   
5. From the left-hand pane, under Manage click Properties. Then from the Properties window, click Delete to remove the selected app.
   
   
6. A message box is displayed prompting you to confirm to remove the selected app. 

Deleting all signatures from the end-users mailboxes

To delete all signatures from your end-users mailboxes:

1. Open a PowerShell window and connect to Exchange Online.
   
   

2. Run the following command to remove all synced OWA signatures:

   $mailboxes = Get-Mailbox -ResultSize unlimited
   
   $mailboxes | foreach { Set-MailboxMessageConfiguration -identity $_.alias -SignatureHtml "" }