[i18n] Some emails not displaying properly (Japanese)

[inter@manse.ca]

I was hoping to get some direction on troubleshooting a particular 
character set, atleast that is what I think the problem is.

I have successfully set up horde/imp.  One of my clients is Japanese 
and they too have been using it successfully, viewing the pages from a 
Japanese version of Windows2K. However, every once and a while he 
receives a message that he cannot read, not matter what View->Character 
Encoding he chooses.

Where should I begin TS?  Is this a browser problem?  A font problem?  
Something on the web server or in the PHP code?  Checking on a message 
that works I see that it is multipart mime with one section being 
text/plain; charset="ISO-2022-JP" and the other (non-working message) 
is text/plain; charset=x-sjis.  I am not even sure if that is is 
relevant?

Any thoughts or direction would be greatly appreciated.  Thank you