Are the email addresses from a purchased list? Mailchimp might find it a little odd that you managed to collect 500,000 email addresses without having ever sent

Are the email addresses from a purchased list? Mailchimp might find it a little odd that you managed to collect 500,000 email addresses without having ever sent out an email before. SES forces you to gradually ramp up send amounts by sending out small amounts of emails over several weeks. Usually people sending bulk email at scale are doing it more than once. Sending out 500k messages once sounds very suspicious. Bronto is a great platform for large sends.