A common question we get at MailChimp is, "how fast can you deliver emails?"
Sometimes it’s just a polite way of asking, "Are you just sending emails from some hamster-powered box in your broom closet?" We point those people to our email marketing infrastructure page.
Other times, it’s because some rookie actually wants to "blast a billion emails a minute" to their "opt-in list." So when people ask me this question, I put one finger on the trap door button under my desk, and ask them, "Um, why do you ask?"
The truth is, our infrastructure does deliver "bazillions of emails an hour," but that’s across all our accounts, servers, and IPs. You’ve got to do it in a very controlled way, or ISPs will think you’re obnoxious, and start throttling or blocking you.
The folks at Strongmail have a nice writeup for this. If you’re thinking about getting yourself a dedicated IP address, then sending tons of emails from it, it’s not quite that easy. Services like ReturnPath’s SenderScore Certified are supposed to help with that, but you’re going to need a good, powerful MTA as your delivery engine first.