If you are looking for holes in stats with CCBill, we don't see it in our stats. This is what our hourly sales graph looks like, for the last 4.8 million hits to our sites. There are obviously early morning hours (Arizona Time) that traffic and sales are both slow, but believe me, if CCBill wasn't processing sales for HOURS, I'd be ALL OVER IT.
Is it possible that the "holes" you are noticing aren't caused by delays in the signup email delivery? (could be a problem on either end)
Steve Lightspeed