Exchange 2010 - Meeting invites sent to a resource from outside organization always as Tentative - anyway to have accept?

Hi -

We've come across a scenario where users who our outside our organization are trying to schedule a meeting and invite the room by it's SMTP address.  The invite shows as 'tentative' on the room freetime, so it's possible that someone else could then 'double book' the room and it be accepted if they are from within our organization.  Any way to have it accept these invites from outside automatically?