I have a list of 35,000 emails that my previous vendor could not validate. He said they were 'unknown' or 'open catch' and he couldn't validate them. However, I know that it is possible to be done because I have taken samples to other firms and they know how to get them verified.
If you are a data verification pro please bid, I will give you a small sample of 100 addresses so you can demonstrate your expertise, and then I will award the project to a vendor with the right skills.
I have projects like this every week so if you are looking for a long term relationship it would be a good fit.