How can I use , ,  tags in a mailing?
Not a good solution but what you can do is disable Advanced Content Filter (ACF) in ckeditor by editing the config.js file in the ckeditor folder like this:

config.allowedContent = true;


See documentation for more info.

What I do is extend the ACF like this:

config.extraAllowedContent = 'html;head;body;span;ul;li;table;td;style;*[id];*(*);*{*}';

[ ] // for attributes

{ } // for styles

( ) // for classes


That way you prevent ckeditor from striping html, body, head, id's or any element tag or even attributes that you need, but it won't add the default html->head->body by default (the behaviour with fullPage = true). The downside is that you will have to add the line on each CiviCRM upgrade, and i don't belive it will work with header/footer templates, I haven't tried it though.