Finally get a response from Yahoo! Publisher Network, after applying for it 10 days ago.
Thank you for applying for the Yahoo! Publisher Network beta program. It is currently in beta and we are accepting a very limited number of new publishers, but we will let you know when we launch to the general public or if we are able to invite you to join the beta before then. To maximize your chances for approval, please make sure:
You have a valid U.S. Social Security or Tax ID number, and web site content that is predominately in English and targeted at a U.S. user base. Your site provides a good user experience. Please see our complete list of guidelines for a positive user experience here:
Your site does not contain problematic content. Please see our guidelines for displaying our ad results here:
Thanks again for your interest. We look forward to welcoming you into our program when it is open to the public.
The Yahoo! Publisher Network Team
Again, they mention about valid U.S. Social Security number. Looks like I'm just wasting my time.
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