Behiavor:
The URL Integration in Outlook does not work anymore.
Solution:
A security update was released in October 2017 by Microsoft. Ths removes the "Homepage" tab from the properties menu from Outlook.
It is possible to reactivate this tab in a registry key:
Outlook 2016:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Security
DWORD: EnableRoamingFolderHomepages
Value: 1
Outlook 2013:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\15.0\Outlook\Security
DWORD: EnableRoamingFolderHomepages
Value: 1
Outlook 2010:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\14.0\Outlook\Security
DWORD: EnableRoamingFolderHomepages
Value: 1
(If the key does not exist, you'll need to create it!)