For some reason wordpress hasn’t fixed a bug in how non-ASCII emails are sent even two years after the bug was submitted. As a result, the subject lines of emails from blogs using non-ASCII characters are sent using unencoded Subject headers. This not only violates email standards, but also tends to cause such mails to be tagged as spam, not to mention that the resulting subject line is unreadable.
Since the wp_mail() routine is one that is plugin-replaceable, I whipped up a plugin based on kpumuk’s solution posted in the bug report. It was surprisingly simple to make the plugin and now the notification emails I get aren’t all scrambled.
Plugin: WP RFC2047