The button sends an email to the mod(s) of the particular sub-forum (e.g. Handguns, Shotguns, General Discusssion, etc.) in which the offending message was posted and also automatically appends links to the post and the thread as well as the name of the member making the report.
In some cases you might get a more rapid response by PMing a staff member who's online rather than hitting the report button.
BTW, Spam all gone.
