How quickly are messages sent out?

Emails are sent out based on an hourly quota. Your hourly quota is determined based on the following schedule: 

If you are a new customer and haven't yet sent out at least 25k emails total:

Once you've reached the 25k mark, there's an accelerated schedule:

The idea is to gradually ramp up the send volume so that if there is any error or problem with the email blast, you can discover it before it goes out to everyone on your list. 

For triggered emails, which are generally much lower volume than blasts, the schedule is as follows: