When you initially sign up your account will be in an evaluation mode where you can only send to your own domains. In this mode you get a total of 1,000 emails. This allotment is intended for testing the product. Those don't renew, but if you run out you're welcome to email us for more. Once you sign up for a paid plan you'll be able to send to any domain. At that point you pay $5/month plus $0.00035 per email. So if you send 10k emails you would pay $8.50. If you were to cancel your paid plan, your account would go back into test mode and your testing allotment (whatever was left from before) would be available again. Let me know if that doesn't make sense!
- Jimmy