Has anyone ever asked you for advice and then told you that your idea was stupid? That’s how Yahoo Suggestions user David Dalka feels after Yahoo not only rejected his suggestion about improving Yahoo mail, but deleted it entirely.Yahoo recently unveiled its new Digg-like Suggestions platform that, at least in theory, allows users to propose ideas and invites the community to vote on the ideas they’d like to see Yahoo implement.Dalka learned that the first rule of Yahoo Mail is you don’t talk about Yahoo Mail — at least not negatively.  After Dalka brought up issues with Yahoo Mail’s spam filters, the Yahoo Suggestions community chimed in with support. Apparently, Yahoo thought more aggressive spam filters were a terrible idea, and deleted the suggestion altogether, saying “the suggestion was not actionable by the owners of the Suggestion Board.”Yahoo may think weblogs are a bad idea too, as that’s exactly where Dalka took his cause. He said, “If this is going to be the normal procedure of Yahoo Suggestions, I now have serious concerns about the success of the Yahoo Suggestions initiative.”