Microsoft Exchange – Meeting requests keeps updating not invited person

One of our clients received an recurring meeting request in Outlook 2010 via Microsoft Exchange 2007, which he then auto forwarded thru a global rule to his private email and accepted it on private account. Now the user claims he keeps on getting updates to his private account even though he has already disabled the global rule of auto forwarding everything to his private account.

While it's easy to blame Exchange for this, or not deleted Outlook forwarding rule,  the only fix for this is to contact the Meeting Owner and get the private email removed from the meeting. What actually happened when the user responded with his private email is that an automated email was send to the meeting Owner with new participant which got processed and saved into the meeting automatically. Any further changes to the meeting are sent to any participant on the list, including the not invited (but accepted) participant.