I’ve been forwarding my personal email to Gmail for a few years now. Google’s anti-spam has been pretty amazing. Lately I’ve been noticing Russian spam getting through. I couldn’t create a filter based upon charset, but found another solution which seems to work great so far:
http://ubuntu-tutorials.com/2009/05/13/filter-spam-by-language-in-gmail/
Creating a Russian-language filter in Gmail:
1. Click “Create Filter†located at the top of your Inbox
2. In the “Has the words:†field, enter: lang:Russian
3. Select “Delete it†within the Action List, and (if you have existing Russian Spam) select: “Apply Filter to Conversations belowâ€
4. Click “Create Filterâ€