This policy of not shipping to non continental military bases/etc. is not new or unusual. It goes back to Army Post Offices(APO) and Fleet Post Offices (FPO) do not really have a "physical" place. Mail is brought to military and dependents by air.
I believe, but won't swear on it, that the USA agrees to not have mailings to APO/FPOs that could interfere with business of that country. This includes Tupperware, Mary Kay, and (obviously) Dells.
I would make a written statement to you unit with copy to Dell requesting some sort of special arrangement. Write your congressment as well; sorry you can't email them...
A group of military personel deployed overseas, including myself wanted to order the new Dell XPS M170 Notebook computer. To our surprise and dissappointment, WE COULDN'T! Dell DOES NOT ship to to military APO addresses! We think it's just a damn shame that Dell doesn't support their military. I guess when a company gets as big as Dell,
military customers don't matter! To make matters worse, we had found a 30% discount coupon code, which really had us excited. That is, untill we found out their policy towards military shipping. So, shame on Dell, for their lack of support for the men and women of the U.S. military!

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