These settings control general download settings which apply to all mailboxes.
This setting controls the frequency with which POP3 mailboxes are checked for new mail. When a large number of mailboxes are set up, consideration needs to be given to the increased bandwidth consumption that will result from increasing the frequency (i.e. lowering the download interval).
This setting controls the maximum number of mailboxes which Exchange Connector will download from simultaneously. For a more detailed explanation of this settings, see FAQ: How does the Maximum Outbound Connections Setting work?.