Well, I did a little digging in the code and it appears there's a bug when Payment is disabled. It looks for purge_type and fails because user_purge_confirm.html doesn't pass purge_type properly.
Here is the patch.
Code:
--- user_purge_confirm.html.orig 2004-05-13 01:37:59.000000000 -0700
+++ user_purge_confirm.html 2004-05-13 01:38:14.000000000 -0700
@@ -8,7 +8,7 @@
<script language="JavaScript" type="text/javascript">
function purge () {
- chkwin = window.open('admin.cgi?page=progress.html;progress_do=action%3DGMail::Admin::Purge::users_purge_progress%3Bpurge_days=<%purge_days%>;purge_type=<%purge_type%>;rand=' + Math.random(), 'status', 'scrollbars=no,width=330,height=150');
+ chkwin = window.open('admin.cgi?page=progress.html;progress_do=action%3DGMail::Admin::Purge::users_purge_progress%3Bpurge_days=<%purge_days%>%3Bpurge_type=<%purge_type%>;rand=' + Math.random(), 'status', 'scrollbars=no,width=330,height=150');
}
</script>
<%endif%>
