It has nothing to do with the old/new system, but thanks.
It has to do with the fact that this problem all but went away, so I stopped moderating new members. A couple slipped through, and bam - we're on some list so now I get 100 new members a day. My inbox is filled with notifications.
What's worse, the ones sending PMs are old - from before all of this, so I'm trying to weed out all the spam users from 1000s of real users.