Hi! I'm ElectricLime. You may know me as the guy who does the Virtual Magic Kingdom articles on
Wikipedia and
StrategyWiki.
I think it's safe *sending* things to strangers as long as you don't give your return address (and I hope I'm not TOO much of a stranger to people around here!). But I can understand your glee at having VMK cards, especially really rare ones like these.
There's a VMK card thread elsewhere on this forum where you could ask to have people send you VMK cards to collect - but that would require you to give your address to anyone who wanted to send you cards, and that's not very safe if you have any concerns about it.