Recently our Sr. Director of IT sent out a Calendar invite to the team for meetings to plan our major project. He sent this meeting to a few select developers and the Operations group. But when he sent to the Operations group, he didn’t expand the group and add each user. He added the Security Group. This caused a serious of errors in Exchange that didn’t permit any user on the Ops group to add the event to their calendars. After being asked to fix this when the person in charge of Exchange was less than adequate for the task, I went searching through the Event Viewer. Found many errors and reduced it to a few that stood out, Error #8217, #8260 & #3005.

#8217 pointed to the particular Calendar event and creator of the event. #8260 logged the inability to access this event using anything other than MS Outlook (OWA and Non-MAPI clients).