Recently active topics in PBwiki tagged with user invitation emails

I have been inviting users to join my Wiki using the Add Users by email page. Some users have complained that they have never received the invitation email. Is this a known problem ? I have no way of knowing exactly which users have received the email and clicked on the link and which have not. Can I be cc'ed on the invitation emails so that I know they have been sent and so that I can resend if necessary. Also I could do with a resend invite facility within the wiki.
This is an urgent problem as it is effecting more users than I would have expected.
Martin