We do not have such feature yet. Before we log it, could you please describe how you'd expect it to work? There are way too many ways of obfuscating, and in my experience, the usual ways of obfuscating - escaping or presenting hex equivalents are not that effective. Replacing even the @ sign with an image equivalents is more effective, thus this is easier to be achieved.
What do you think?
On a side note, if you wish to implement this yourself, I'd suggest you the approach with the at (@) sign. The RadEditor exposes some hooks on which you can attach - on client paste, or on content area change (I do not the exact hooks by hear, but wanted to let you know on the approach).
I hope this helps.
the Telerik team
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