Disable email signatures in Outlook Web App (OWA)

By default, users are allowed to create and modify their own email signatures in Outlook Web App. To prevent this, a policy can be created, which disables this feature for all users.

Creating the policy

1. Navigate to https://admin.exchange.microsoft.com/.
2. Open the Roles dropdown and select Outlook web app policies.
3. Add a new policy or edit an existing one:
   • Under Select features, and the User experience dropdown, uncheck Email signature.

Disable active user signatures

In case users have already added a custom signature, following the above steps will not disable the existing signature from being inserted by Outlook, only disable the access to create new signatures. To disable the automatic adding of user signatures the following PowerShell script can be executed to automate the process.

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