Not in my view. This information is given out to anyone who requests it, without signing of a non-disclosure agreement.
In most countries the recipient of mail can make the message public if he decides so. Usually considerations regarding privacy must be made however (you can't reveal legally confidential material, such as medical records). A company writing "confidential" on some document doesn't make it legally confidential, especially if you're willing to mail it out to anyone and everyone.
I thought they had only mailed it out to those who had expressed an interest in the beta test programme?
Had it been mailed to anyone and everyone, then I would have received a copy. I have not.
You don't consider it confidential, fair enough. Do you consider it ethical to make a message public when the correspondent has marked it confidential?