I would make a new address for the recipient. Send it directly to his email account after using 7zip with AES encryption to compress the text file containing the details, and a long password that is exchanged through a different medium than email. Many can potentially read forum private messages and even email, you need to know that nobody but you and adamas can possibly have the private key.
Normally I just use query on IRC to pass this information, using IRC over SSL. To be honest, I very much doubt that the forum administrators are going to steal a few BTC and risk jeopardising their positions on the forum or the forum's own reputation.
I'm far more concerned that somebody gets ahold of Adamas's password and looks through his PMs, which is why I told him to delete it once he's successfully imported the private key.
Confirming that I've received the 1BTC from Adamas.