Can you email us about this? [email protected]
The reasoning is that yesterday someone was crawling every possible page on Rentry by trying all the URL combinations, which was hammering our database server to 100% capacity. So I added a block for anyone meeting these criteria:

Tries to load 3 pages that do not exist where the URLs start with 'g' within a timeframe

Is using Firefox/Chrome on Mac

Initially it blocked 200 IPs but it's now at 20,000, which is still possible with these crawlers using an IP proxy service. I'll flush them now and add some more to the criteria