You want to have Outlook signatures updated by Exclaimer O365 Edition in addition to Office 365 OWA signatures.
In addition to the updates to Office 365, you need to push an Exclaimer agent to your Desktops. The best method is to create a GPO to push the Outlook signature update Agent install.
- Downloaded the Outlook signature update Agent MSI from:
NOTE:you will need to scroll down a little see screen shot below
- Create a GPO to push software to your Windows Desktops for the Exclaimer agent.