Recently my phplist installation v3.0.12 started doing weird redirects. For instance when I click to start a new campaign it redirects back to my website. Also, when I go to the login page another user entered their email for a password reset, it sends a token to my email and when clicking on that link it redirects to my website and not a password change form.
Have you enabled error trapping on your site, nothing to do with phpList by the way. I ask this as if you have, (check your site .htaccess file) if phpList encounters an error, rather than allowing you to see what is happening, a site wide errordocument 404 will often redirect to the main site.
Also, if your phpList is installed on the same computer as the website, it could be that the install directory setting in the config.php file is not set properly… here’s an example if you put it in the /lists directory
# if you change the path to the PHPlist system, make the change here as well
# path should be relative to the root directory of your webserver (document root)
# you cannot actually change the "admin", but you can change the "lists"
# DO NOT include the file eg "index.php" because that is added when required. If you do
# it is likely to break the tracking, see http://mantis.phplist.com/view.php?id=15542
$pageroot = '/lists';
$adminpages = '/lists/admin';