I wouldnt send it in the mail, but if you do dont send it in a package. Get some hash and flatten it and put it in a birthday card. People are less likely to check cards that look like regular mail than they are to check boxes.
And don't put a return address on it, and send it out to an abandoned how near where you live. That way if shit gets fucked up they wont know who sent it or who is supposed to receive it.
All I know is that when I left Amsterdam I got strip searched by the fucking French. There were 80 people on my bus - Chinese, French, English, German, Dutch, Indian...tons of people. But the only people that got strip searched were the Americans (fuck the French). They went through everything we had and when they realized we were coming from Amsterdam they had a FIELD DAY with us. So if they're gonna check Americans just to fuck them, you better believe there's a chance they'll check most of the mail going to America.
Your best bet is to get a Zippo lighter. Pull out the cotton part in the bottom where you're supposed to fill it up with fluid, and put a few grams of hash in there. Then just through the Zippo in the bottom of one of your bags. Customs will never go as far as to open up a Zippo. But then again...I never came across any dogs at customs or the airport.