one thing that has bugged me in the past: upas relies on file -m to determine the type of attachments, but file only reads the first block of the file, so if you've got a utf-8 file with the first non-ascii character beyond the 8192nd byte, you get corrupted mail.
IMHO for the -m option, file should probably read the whole file, but there are probably good reasons for not doing so.
