Hosted Exchange Distribution groups i am part of

Hello,

I have setup a Hosted Exchange environment, i am filtering on ExtensionAttribute1 between company's.

Now when i create a Distribution group with ExtensionAttribute1 filled in this is still displayed when a users goes to OWA --> Options --> Groups When the user clicks on the butten to let him decide where to be a member of he will see all Distribution Groups there are, regarding what i set in ExtensionAttribute1, so i have to hide all my Distribution Groups.