Automatic Extension

I have a quick question about the automatic 2-month extension for filing Fed taxes. Does anyone know whether I need to change my address with IRS for that extension to be recognized automatically? I'd hate for them to be waiting around for my forms (they'll owe me $$, so that's not a problem). I lived in the UK for 2 years 8 years ago, and my recollection is that I just sent my tax stuff in June -- perhaps with a note about why I qualified.

I always write 'US citizen filing from abroad' across my tax returns and I've never had a problem. I always filed the change of address form with them as well however, as we moved several times in the first 2 years I was here and I wanted my rebate check to be able to find me.