i want to buy email list

Hello, i want to buy a big email list , at least 250,000 emails, the more the better, conditions: 1- they should real emails, every email for one person, not all created by the same person. 2- they should be 2 times opt-in if they are sorted by any carteria will be great, bid for 250,000 emails. i will not pay or escrow till i check that these emails are real emails not garbage, i may need 48 hours to check that. thanks,