This article describes steps to reduce the amount of messages in the Collaboration Services service mailbox.
You need to change Session timeout value. If this value is more than 0, then after retrieving the specified number of messages, Collaboration Services will stop the current session and wait for the specified length of time. Having an interval between sessions may help decrease the load on the Exchange server.
You need to set 0 for Session timeout value. If the Session timeout value is 0, then Collaboration Services will retrieve messages continuously until all available messages are retrieved from the mailbox.
