I just tested about 100 email addresses (with a relevance of 10) and got about a 50% hard bounce rate. I.e., these email addresses are invalid and I got a warning that if my bounce rate stays at this level, I will lose the ability to send emails (via SES shared IP). It would be immensely helpful if you could validate email addresses in your database with some throw away IP addresses so we don't have to do that.