mail subj. won't allow double byte chars

[Anon]

I am writing a mail system for a Japanese client.

The problem that I am having is that the mail() function in php is not allowing the subject line to contain double byte Japanese characters. I have tried the addtional headers of mime and content-type, but this only affects the message and not the subject. Anyone have any ideas?

This mail system will be hosted on an english FreeBSD server running Apache and MySQL if that info helps.

Thanks,
Andrew