Many thanks for all your valuable comments.

If the IRS does not outsource its mail to Estonia, this makes the letter a real fake.  

FYI, the contact numbers that the letter suggests TP should call for questions are the IRS numbers (800-829-1040 and +1-267-941-1000 for outside the US).  However, the SSN is not truncated at all.  The letter has no notice # but letter #.  Also, the mailing address of the requested information is Mail Stop 6126 AUSC, which is different from publication 1546 (3651 S. Interregional Highway 35
Stop 1005 AUSC Austin, TX 78741) as suggested by @qbteachmt.

As I do not have PoA Form 2848, I would suggest TP to make a verification call to the IRS (+1-267-941-1000 the IRS International Hotline).  If the IRS letter is legit, we will respond.  If not, we will ignore.  Please comment if you have on this.  Thanks.
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