A couple of weeks ago Google apparently has implemented a new way of detecting spam. Even though the IP addresses used by the bmwe21.net servers are marked as safe and trustworthy wherever you look, probably the URL's set their alarm bells off. I guess their current developers have never heard of a php forum.
Anyway, I have tried all means I could find to report this to Google but no response at all from these tossers. So please be informed that you may not receive the forum's notifications.
GMail mailservice wrote:Our system has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked.