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I think you're right to keep them on the site.  The biggest reason is probably so that people can still have access to the information through search and other means.  As for linking to them from the site, I think the same idea applies.  If you get a new follower and they love your content, they may want to read all of your historical posts.  And you shouldn't make it difficult for them to do that.  When I first discovered what is now one of my favorite blogs, I went back and read every post since it was started 3 or 4 years earlier.

The error appear on a set of URLs that are not valid, and our CMS result an error (a bit like a 404 except that it is not a 404 but a url with bad parameters) So all these url goes to the same error/warning page dynamically generated by the CMS but there is not a redirect. Something that can happen for instance on access denied for protected content. My bet was to place this <meta < span="">name="robots" content="NOODP,NOINDEX,NOFOLLOW" /> on this page.</meta <> SEOmoz tools still report the error of duplicate content. I could of course also set a canonical but I have no idea of which URL to use for it. Exemple of link: http://www.nuxeo.com/en/about/events/jan2011training-boston/moreinfo

Looks like we had a minor bug and it got fixed last night - you should be able to see the duplicates now. I checked out a couple, and we're crawling a few tracking parameters in URLs, such as: utm_source=enews&utm_medium=email&utm_campaign=enews20120117 Looks like these might be links in an e-mail newsletter? The good news is that Google is pretty good about ignoring these, and it looks like your canonical tag is properly configured. I think we may be reporting these too aggressively. As far as I can tell, you should be ok.

Thanks Kane, Aran, We will try to do that!

You will see that in GWT. Go to GWT > Crawler Access > Remove URL. It'll de-index that 404.

Hi there, The URLs are viewed as different due to the campaign tracking variables being appended to the end and hence it appears as though you have duplicate content. You can resolve this by using the canonical tag. hope this helps!

Here you go buddy. Short answer is yes, but it will take 24 hours... http://seomoz.zendesk.com/entries/20034082-crawl-diagnostics