I have closed Q2A site too.
Although conservativeness is not so good, I redirect by theme. If it is made as follows, redirection feature of qa-login.php will process correctly direct link of notification e-mails. Keep in mind that it may not move correctly depending on the reconstruction state of core program.
Exp code) qa-theme/YourTheme/qa-theme.php
function doctype() {
if (qa_get_logged_in_userid()===null) {
$req = qa_request();
if ($req != 'login'
&& $req != 'register'
&& $req != 'forgot'
&& $req != 'reset'
&& $req != 'feedback') {
if ($req != '')
qa_redirect_raw(qa_path_to_root().'login?to='.$req);
else
qa_redirect('login');
}
}
qa_html_theme_base::doctype();
}
I am pleased if it becomes helpful.