We host our Exchange and Lync community calls and send the invites out via DL’s. Generally this has been good and a major improvement over trying to maintain the list of invitees within the event itself. However, it’s far from perfect, people end up with old/stale invites, don’t get updates, get forward the invite so never receive updates etc. The solution, to my mind, is a calendar that people subscribe to – that way they get semi-real time updates, there is a single version of the truth, and people can subscribe and remove themselves as needed. I worked out that I can share a secondary calendar to everyone, and they can subscribe (sort of) to it without too much ado, but it doesn’t have reminders in Outlook – so it’s basically useless. I’ve seen method using SharePoint calendars combined with RSS feeds that allegedly work – but then the updates only go to devices with access behind the firewall, unless we create a unique SharePoint site just for this.