Outlook 2007 not showing Meeting Request Voting buttons

We run Windows Server 2008 with Exchange 2007 and Outlook 2007 AND GFI MAILESSENTIALS 2013. When MOST of our users send out a meeting request MOST of the recipients receive the email but with no voting buttons. They cannot Accept or Decline the meeting and it does not get added to their calendars. There are a few users who will see the buttons when they receive the invites from certain other users.

No one has Automatically Accept checked in their Calendar Options.

Under Calendar Options when you click on Scheduling Resources it says
The folder cannot be opened because there is a configuration problem on the server.

Frankly I am at a loss especially since it works for a few people.

Any ideas on how to get our response buttons for meetings?

**UPDATE**

We have narrowed it down to this. When a meeting request is sent to internal users that DO NOT have their emails Forwarded to an external address/receive local copy via their Mailbox in Exchange, then they all receive the invitation with the Accept buttons.

If a single internal user that does have  their emails Forwarded to an external address/receive local copy via their Mailbox in Exchange is added to the invitees then NO ONE will have the buttons including the other users who otherwise would have.

Also, we have GFI but do not have Disclaimers turned on for calendar meetings.
emscbAsked:
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