That means if you email the posting gateway in Russian, and your mail's in KOI8-R and not UTF-8, well... it won't work.
So: help us fix it by sending me mail in different encodings! firstname.lastname@example.org
Please check the comments on this post before you do, though. Reply when you've mailed me, including what charset.
Outlook / Outlook Express with MS-characters (quotes, dashes, apostrophes)
Russian in different encodings
webmail stuff (hotmail, yahoo, etc)
And what's this text/plain; format=flowed stuff?