Disable Outlook on the web (OWA) signatures
This article applies to Exchange Server 2013, 2016, 2019, and Exchange Online (Office 365). For older versions of Exchange Server, i.e. 2007 and 2010, see this article.
You would like to prevent users from creating individual Outlook on the web (OWA) signatures and adding them to email messages.
To prevent your users from adding their own signatures in Outlook on the web, you need to disable the Email signature option in the Outlook Web App mailbox policy assigned to these users. To do so, follow the steps below.
For this solution to work, you need to make sure your Exchange/Office 365 plan supports Group Policy (GPO).
- Log in to your Exchange admin center.
Go to permissions > Outlook Web App policies (see Fig. 1.; the interface is similar for all current Exchange versions).
- Double-click the policy that is assigned to the users for whom you want to block custom OWA signatures.
See this Microsoft article to find out how to assign Outlook on the web mailbox policies to users (mailboxes).
- In the window that pops up, navigate to features and expand the list of features by clicking the More options link at the bottom.
On the list of features, find the Email signature checkbox (Fig. 2.) and deselect it.
- Click Save to apply the changes.
Note that that disabling email signatures in this way does not remove signatures that are already configured. You can use PowerShell to remove all OWA signatures - see our article to learn how to do so.