I ship overseas on a regular basis. It is perfectly safe. I have never had a problem and sometimes buy pins for people in Ireland, England, Finland, etc.
I trade all the time and never have a problem. I do tend to make my packages more secure though with lots of external tape so ripping is not an issue. Also, think about who you are sending to because when customs see's more than $40.00 on the form, they tend to take much longer and your receipent may have to pay major duty. Since you cant insure to most of these countires, do them a favor and never put more than $35.00 - $40.00 on the customs form.
Their pins will usually get to you in half the time yours take to get to them. I have gotten tons of my best pins from these people in other countries. It is especially good to have friends in Paris, Hong Kong, Tokyo, etc too.