Recurring meeting in Outlook sending updates automatically to all recipients

Question

We use Outlook 2007 with Exchange 2003 SP2 cached mode.  We have a project team that schedules meetings for working groups that include some people in our organization and several from other companies.  With only one user we have an odd recurring meeting problem.  When our employee creates a meeting, makes it recurring with an end date, adds recipients and sends the meeting out, the recipients receive it and reply.  All is well. 
However, at random times, even when Outlook isnt connected to the system, Exchange sends a duplicate meeting invite to all recipients again, and they all reply again.  This time, their replies are different.  We receive a reply for each occurance in the series rather than just a single reply for the series.  Some recipients are saying that they received 6 invitations from us instead of one, and had to accept each one.  This happens about three times per meeting.  Another thing we noticed is that the End Date on the series is changing.  We wondered why updates were being sent out if nothing had changed and realized that the End Date for the series was incrementing by one day.  For example, the series was supposed to end on Nov. 21st when our employee sent out the message.  The End Date changed to Nov. 22nd and Exchange sent an update to all (This was on a Saturday that this happened.)  There were more updates sent by Exchange over the next few days and each update had added another day to the End Date.
Any ideas why the system would send updates to meetings on its own and change the end date? James Nelson

Answer 1

We are experiencing the same problem.  Four times in the last six months or so we've had iPhone users send out Calendar items that end up resending over and over and over.  This is on Exchange 2003.  The calendar items were each created in Outlook 2007 and involved multiple invitees.  Some of these items were reoccurring events, others were not. 
What we have found is that when the owner/creator of the calendar item deletes the acceptance emails from the invitees, that is when another calendar item is sent out again.  This also happens if the acceptance email is moved to a subfolder.  In other words:
Jane creates a calendar invite and includes Bill and Bob.
Bill and Bob each accept the invite and an acceptance/confirmation email is sent to Jane.
When Jane deletes Bill's acceptance email another calendar invite is sent to both Bill and Bob.
When Jane moves Bob's acceptance email to a subfolder...another calendar invite is sent to both Bill and Bob.
The only way I have found to stop the invite for re-sending is to delete the original invite and start over, or for the sender to not delete or move the acceptance emails.
I have not figured out what causes this problem.