Brain teaser.. really a good one to make you think...

This is a very difficult puzzle..
i would like you guys to try it and improve your analytical skills..
The answer to this puzzle is an english word. the answer will be given at the end of this mail.. but i advice you not to go for it immediately without even trying..

now here it is..

IT is a 7 letter word...

If you remove one letter from it, it remains the same..

If you remove two letters from it, it remains the same..


If you remove three letters from it, it remains the same..


If you remove four letters from it, it remains the same..

Even If you remove all the letters from it, it still remains the same..

guess the word...

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The answer is....




POSTBOX.....ha ha ha.. thoppi thoppi..:-) :-)