Why do I need to know anything at all about the link structure beyond the domains?
If the user requests (from a link in the mail) "mkt5371.evernote.com/foo123", redirect to "links.evernote.mkt5371.com/foo123"; If they request "/bar456?id=asdask", redirect to the same query under the mailer's domain.
If the user requests (from a link in the mail) "mkt5371.evernote.com/foo123", redirect to "links.evernote.mkt5371.com/foo123"; If they request "/bar456?id=asdask", redirect to the same query under the mailer's domain.