My public Bluebottle e-mail account (firstname.lastname@example.org) has stopped 5k spammers so far (since 05/31/2005).
Every e-mail sent to that e-mail is checked for a human sending it, and senders that correctly identify themselves are permitted through. Any other is filtered out to a "Pending" list. I periodically visit that list, and check the non-spamm ones (a few, if any). The rest is put in to a "Blocked" list, and any further e-mail from these senders is quietly dropped (any time I connect to Bluebottle I see a message saying "213 messages thrashed" or something like this, meaning that since the last visit, these many messages were received (and dropped) from the already Blocked addresses (I guess).
So it is this "Blocked" list that has reached a count of 5004 addresses on it. Obviously, many more spam messages were received (more than one from each address). My first spammer in Bluebottle:
Kendra L. Brown
Long time no see, Kendra!