Unfortunately, I was inaccurate and used not quite correct ways of saving the attached file.

That is, if I saved the attachment with RC menu, everything works correctly. But if I tried to view the attachment or save it by browser command, then the embedded html file is displayed and stored incorrectly.

The Hex codes of ciryllic leters are different when I saved them with RC and browser commands. The fact that the RC command "save" is output as D0 A1 D0 BE D1 81 , when saved by the browser (and, probably, when displayed) has the value D0 A0 D0 8E D0 A0.

However, it seems that this newsletter has already died and I'm trying in vain.