Try this plugin in the store for free "external linker". I just gave it a try on my test site. It seems to work well. I had some other js code in the post, but found that it interfered with the chat window.

http://www.oxwall.org/store/item/291

Found an issue with the "External Linker" plugin. It doesn't play well with the "Add New" links. I found a js code that works good except for two links, for me anyway, in the "Add New" links. They both have javascript links with target="_blank". They both open a blank page. If I edit the code in inspect element, and remove the target="-blank" they open fine. I'm trying to search for a work around for this type of link, but no luck so far.

I think I have found a successful script that works "even all of the add new links". Everything on the site seems to work, and external links open in a new tab.

I just put this in admin / settings / page settings / body

<script type="text/javascript">
$(document).ready(function(){
 var isInternalLink = new RegExp('/' + window.location.host + '/');           
 var h = window.location.host.toLowerCase();
$("a[href^='http']:not([href^='" + h + "']):not([href^='http://www." + h + "']):not([href^='mailto:']),a[href$='.pdf']").attr("target", "_blank");
   
});
</script>

Darryl, 

you might consider wrapping that in 
{literal}
{/literal}
i don't know if you need to in that section but i always wrap my scripts in that within the html files so it might be the same :)

It was working as is, but I put your suggestion in as well. Everything still works well.

Great, its just that smarty at times can be fussy, and i dont know how that section you posted the code in is parsed or filtered which is why i am not sure if needed or not. 

http://www.smarty.net/docsv2/en/language.function.literal

I just know that in the html file itself its always best to wrap it.  Its probably just fine your good at what you know buddy.  Its just an extra precaution i guess. :)

I looked the literal tag up. I had seen it before, but haven't really looked to see what it's for. Guess it is good to use it around scripts, just in case.

I just noticed that the {literal} tags were displaying as text at the bottom of the page. Didn't really notice it until now, so I took them out, and re-posted the script above without them.

strange... but glad you caught that i didnt notice that either

It appears from a little more reading on them that placement of the tags is important. Maybe they respond differently when they aren't local. Several examples used the tags within the script, and not just encasing the script with them.

sometimes its {literal} which is smarty i think and the normal is <literal> cause i have it on a test page now as <literal> and its not showing, interesting