You can send an image of your data rather than text, but they could still
type it from your image if they wanted to. There's really no way to
absolutely prevent someone from them from getting your data into a format
they can edit. Other than not sending this to them, your most effective
technique may be to send copyright notice with your material. You might
want to do some research on copyright law. I believe that, if you're the
originator of written material, you have copyrights and you do not have to
file some document with the government to assert this right. However, I
believe there is a formal filing procedure that can be used as addtional
protection of your rights should you wish to take legal action against
someone based on infringement of copyrights.
