I think that the idea of making new penfriends is great, but I would advise you to do it through some kind of system that conceals your real contact information, such as the pm's here or elsewhere.
Unfortunately, sometimes you never know who you are communicating with and there are some people out there who don't have your best interests at heart. You can write back and forth via pm the same way you could via email, only your real email address will be concealed.
Once you get to you know your penfriend well enough, and you are confident about who the person you've been communicating with really is, you can always exchange email addresses and correspond that way.
I don't mean to scare anyone... we've all heard stories about safety and suggestions of precaution on the Internet. I just want to see members of the Horse Forum family be safe and happy! :)