I talked to Habeas and Return Path, but for a start up that doesn't have a ton of cash, they are too expensive. For delivery monitoring and whitelisting, both services are well over $10,000. Instead I opted for
www.deliverymonitor.com - they don't provide much support, and if your emails don't get delivered they don't do anything for you. BUT, they do give you basic feedback on whether your emails are delivered to most major email providers and ISPs. AND, they have a 30 day free trial (after that it's $80/month, but I might just cancel bc all my emails are being delivered :)