Double click Barracuda Essentials to open the App Settings dialog box and specify the user defaults. Go back to the Organization > Add-in section in the Exchange Admin portal.Fill out the required fields and select the check box to consent to the terms of use.
Select Barracuda Essentials for Outlook from the Suggested Apps results.
For more information on how to install an add-in for your Exchange version, see the Microsoft article. The instructions below use Office 365 to install the Outlook Add-In. Note that the user interface will vary depending on the Microsoft Exchange version you are using.