I have all the tax documents ready but am not sure how should I mail the documents. I was thinking of fedex but since IRS address is a PO Box address, not sure fedex would deliver.

What would be the best way to mail to documents to IRS from here in India.

If you are getting a refund, mail it normal mail. The cost of FEDEX or any other courier service from an overseas country is prohibitive (often in excess of $100).

If you mail it normal mail, it more than likely will get to the IRS eventually. You can start checking the Where's My Refund? Application weekly on the IRS website about two month after you mail it. If your return does NOT show up after three months, then mail the return a second time.

For 2009, you have until 15 April 2013 to claim the refund, so sending the return multiple times via normal mail at about $3 per mailing beats sending it via FEDEX for $100.

If you OWE taxes, then (and only then) should you consider using FEDEX.