rel=”external” is now the XHTML valid version that informs search engine spiders that the link is external. However, using this does not open the link in a new window. target=”_blank” and target=”_new” does this, but is not XHTML valid. This very simple plugin adds a small JS file to your header to let this happen! rel=”external” plugin homepage. More WordPress Plugins. Facebook Comments Plugin Twitter Feed Plugin Follow @alexmossSEO on Twitter. Alex Moss. Pleer SEO.