Thus spake Philip Beach:
Surely there are many different ways to do this but the most straightforward way would be to place all the email addresses in a page only viewable by logged-in users. Search mediawiki.org for user rights management.
Sorry, but neither setting the whole page to be viewable only by logged-in users, nor splitting the page into two are an acceptible solutions. One of our goals in switching is to put everyting on one page (it's on four pages now).