Do you think it is ok to hit on girls through the internet?...like facebook?

Just curious. There are some girls who i only see through facebook, i would like to talk to. My problem is i am pretty straightforward, so when i say things through email, a lot of times they come off as creepy or just plain rude. plus when your not face to face it's a lot easier to ignore someone...So back to my question. Do you think it's ok to email messages to girls you don't really know and say things like, "Hey i think your kind of cute, want to talk?"