I have a website that allmost daily are creating a new "item" (Job posting) and again allmost daily deletes one of the finalized items.

I would like the visitors to return to a "This jobposting is now closed, in 5 seconds you will return to a list of all available jobs) - I think it should return 404 (410?) - Would like Google to remove the index of this site, and not keep it indexed.

Any ideas ?

I would like this to be only running for K2 items the have been removed - So I have a 404 page for the "normal Joomla section"

Hello Steen,

You need to do several things to achieve this.
You need a sitemap extension which suports K2 (xmap has a really good K2 plugin),
then edit the error.php so it has a meta tag for redirecting.

Unfortunately Joomla! has only one error page so you can either develop a common error page for all compoents with the redirect or, you can alternatively use the redirect plugin or an SEO/ SEF extension like sh404sef to redirect these URLs to a custom URL or a custom view.