How to get permission without getting permission
Question: I've found a great file on the net and I want to use it in print or at my site. But every e-mail I've sent to the copyright holder gets ignored. No replies. What now?
Answer: Make sure you offer to credit them, link back to their site, or both. Be very diplomatic. Keep copies of each e-mail you send. After your third or fourth attempt try language like this: "I've not received a response to use your file. Nor a response of any kind. While you haven't granted permission, you have certainly not objected. Unless you object now I will go ahead with the use I have planned. I consider this e-mail a release. Have a nice day."
Do you now have a legal copyright release? No. But you do have a nice paper trail that displays a good faith effort on your part. And a complete lack of vigilance to defend their copyright on their part. Go ahead and get on with your project.