The RecentMessages property returns the number of messages
which have been recently added to the currently selected mailbox.
This property is particularly useful when the INBOX mailbox is
selected, since it enables the application to check if any new
messages have arrived.
This property value is only meaningful when connected to an IMAP
server. If the control is connected to a POP3 server, this property
will always return the same value as the MessageCount
property.