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When navigating to Administration -> Settings -> Advanced -> Appearance there are two input fields that control the content filters for the rich text editor. One of the controls it only for the content block widget. To make sure that the correct filters are applied everywhere make sure to specify them in both "RadEditor filters for Content block widget
" and "Rad Editor's content filters
By setting both of these fields to None I was able to insert "<i>" tags in the blog post's content field correctly (normally i tags are replaced with em tags).
I hope the above information helps. Please do not hesitate to get back to me if you need further assistance on this matter.
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