Because you don't know what that "/anything" is, only your mailing system does, and it converts links in your email template to these mkt5371-type links right before it sends out the email.
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.