I’m reviewing Exclaimer Cloud and during the process, I noticed that by default the end-user has the ability to configure signatures and kind of messes up an e-mail signature solution. In this tutorial, we are going over the process to disable such feature of OWA, we can also disable signature on the Outlook client using Group Policies.
Logged on the EAC (Exchange Admin Center), click on permissions, and then click on Outlook Web App policies. Double click on the desired policy.
Click on Features, and then click on More Options.. in the list that shows up, make sure to clear the option Email signature. Click on Save.
It is that simple to disable the ability of an end-user that is affected by that policy to configure their signatures using Outlook Web App.