- You request a read receipt for all sent email messages in a Microsoft Exchange Server 2010 Service Pack 1 (SP1) environment.
- You send a meeting request to a recipient.
- The recipient accepts the meeting request.
After 120 days, the Microsoft Exchange Mailbox Assistants service deletes the messages in the recoverable items root folder. This generates one or more NRNs if the SuppressReadReceipt flag is not used.
Note The NRNs are not completely flushed until 120 days have passed after the hotfix is installed.
SuppressReadReceipt flag, visit the following Microsoft website: