An Exchange Server message routing myth forever being propagated (including by me):

If 2 SMTP Connectors (or Send Connectors in case of Exchange Server 2007) exist, one with a more specific address space, like exchangepedia.com, and one for a more generic address space like *, messages are always routed over the Connector with the more specific address space.

http://exchangepedia.com/blog/2008/01/smtp-connector-myth-messages-are-always.html