We are currently using Mailchimp and are looking to move to a more robust tool. We are sending ~15M marketing and ~12M transactional emails a month. We need something that connects to our homegrown marketplace so we can serve custom recommendations and content for users based on on-site and other actions.

Anyone have recommendations for this scale?

Would love to hear what people are using and pros/cons. If you had time to hop on a call I could make it worth your while :)