Here is the procedure for a temporary test… Please note any local modification will be periodically override by GPO policies (every 90 mn). This procedure is very reliable as far as you do not forget to cross-check GPO settings have not been refreshed while testing your local tweak. This is the method I use myself for quick test.
Therefore the following cannot be communicated/used as a permanent work-around for end-user, it is just for test.
Basically, you need to modify entries that can be found in:
If you have a look to the existing entries, vs. what is applied through GPO settings, you will quickly understand how it works. Then all you have to reminder is that “2” is to assign to “trusted sites” zone.
In following example, you do see the implementation of *.adp.com assigned to trusted sites zone.
Another example. Below is the result for *.checkin.lufthansa.com
Create / modify entries as required for your test. Each time you make a modification, you must close all existing IE windows and relaunch IE to load the new list.