We have a 2010 Exchange Server in a 2008 R2 Windows domain. One of my users has requested that 2 people who are not employees and, therefore don't have accounts in our domain, have access to his calendar. For compliance reasons, I can't create logins (no matter how restrictive) for these 2 people. Training everyone else in the firm to send calendar invites to 2 attendees (email@example.com and firstname.lastname@example.org) would be near impossible. Is anyone aware of any utility that might do a realtime background sync of an Exchange calendar with a calendar hosted outside our domain? The user making the request is a senior officer in the firm - otherwise, I would have said "No" right off the bat!!