what do you hope to achieve by doing that?
e: if you're writing what basically amounts to a suicide note and sending it to them electronically, you can go about it how the user coldbed described below. i would add to it, however, that this was your own decision, that you were not coerced or influenced, and that you were the only one involved in this process. all this being said, i don't see why you wouldn't just leave a written note at the scene - you avoid any potential security / privacy issues this way as delayed emails have led to rescue attempts in suicide cases before.