Is there an email service that allows you to nicely query your own database to create the recipients list? The issue is that we do tons of specialized user segmentation to create lists of recipients. Trying to keep our database in sync with the email-service's database is risky and fraught with potential issues since user data will be updated frequently in multiple ways. But we still need the powerful features of a service like SendGrid or Mailchimp where such as A/B testing, open & click-rate reporting, WYSIWYG template design, etc.
My pipe dream is to have a service like Sendgrid or Mailchimp, but when it asks you who to send the email to, you specify parameters that you've created yourself. It sends these parameters to your server, and your server (using a little code that you've custom-written), performs a query on your user database and sends the recipient list back.
Does such a service exist?