...and I don't mean varicella zoster.
I'd previously seen systems that, in their zeal to eliminate unwanted commercial content, have also eliminated the ability to type words such as "socialist" and "specialist" (hint: they contain as a substring a popular pharmaceutical name). But this is something new to me. We've all seen sp'm th@t rep/ace$ characters of words with other typographic symbols in order to make them more difficult to filter against, right? And the filtering software tries to detect patterns that look like words with replaced patterns, calling them "chickenpox".
Apparently the filters on these filtering systems have become so effective that they will also detect the same chickenpox pattern in other contexts, and in particular in marked-up LaTeX manuscripts, something like:
That's right, best not to type mathematical formulae in your emails, especially not brief mathematical formulae involving subscripts formatted so that TeX can typeset them, or your recipients won't get them.
All I can say is it's a good thing those same filters aren't applied when checking files into and out of cvs.