The tone and wording used in the auto-generated email shocked me. I would be pissed if that had been sent to anyone I know.
Saying that the content of the email "should be more explicit" is an understatement of significant magnitude, and it glosses over the crux of the issue. The site clearly betrayed the OP's trust, and had I been in his shoes I would have felt the same way.
My comment was made prior to your edit which added mention of the "tone" and the "from: field".
I have also up-voted your comment, although I strongly disagree with the conclusion.