The Messages tab shows a list of all the messages that have reached the system but were not rejected. Messages are kept in the list for a period (8 days, by default), and then message records will be deleted.
On the left side of the messages screen, you can choose to view messages according to one of the following message status:
All Messages: All messages that are in the system.
Quarantined: Messages that have been quarantined
Discarded: Messages that have been removed from the system.
Outbound: Messages sent from the system.
Quarantined and Rejected are pre-applied filters to contain only this type of messages.
The Outbound (messages sent) lists the messages that were sent from networks authorized to relay mail through MPS. You can change all views by applying certain filters.
Note about Rejected Messages: The Rejected filter lists the messages that were rejected before the Mail filters.