I have noticed an enormous amound of newly registered members who never logged in but still are able to use my mailserver to send emails using my forum as sender...

I have to manually delete all those members (approx 30-60 per day!) without them showing up in the total of registered members and without notifying me as administrator...

I only see them when I look in the admin area and sort logins having all zero's at the top of the list before selecting them.

What can I do about this?

Bert