I found that invoking the "Email" URL (as opposed to "Reply" or "Forward") will always use whatever is in the "Correspondent" field, so I whipped up the following BugMonkey script that appends an "Email" link to the "Correspondent" heading.
name: Email
description: Add email link to correspondents
author: Marcelo Cantos
version: 1.1.0.0
js:
(function() {
var f = function() {
var ixBug = $('.ixBug a').text();
var corr = $('#idCorrespondentInfoBox label');
if (ixBug.length && corr.length && !corr.next('a').length) {
corr.after('\
<a class="actionButton2 icon" onclick="return TabManager.clickChangeView(event, \'email\');" href="default.asp?pg=pgEditBug&ixBug=' + ixBug + '&command=email&" onmouseover="return true; return true;" onmouseout="return true;"><img src="images/email.png" border="0"></a>\
<a class="actionButton2" onclick="return TabManager.clickChangeView(event, \'email\');" href="default.asp?pg=pgEditBug&ixBug=' + ixBug + '&command=email&" id="email0" command="email" onmouseover="return true; return true;" onmouseout="return true;">Email</a>\
');
}
setTimeout(f, 1000);
};
setTimeout(f, 1000);
})();
The usual caveat: it is almost completely untested and probably doesn't handle all kinds of important edge-cases. But at least it will keep my boss (who I assured FogBugz could broadcast announcements to per-case customer groups) happy.