Is their a limit on how many can go in at once?
Using Yahoo, you can send two full blocks before it tells you to wait an hour. I sent two blocks and readied the other block emails as "drafts" for sending a few hours later.
You will get about 30 emails bounced back, but you're still sending a large number quickly and successfully. I'm going to revise the list tonight to remove some addresses and change others. I'll post the new list in this thread.