I'm running Postfix MTA with content filter based on Apache James, whenever Postfix relays a mail to the content-filter, for example with UTF-8 From field, it fails to deliver the mail to Apache James with error:
Sep 08 16:58:37 redacted postfix/smtp[214]: REDACTED: to=, relay=content-filter.redacted.net[REDACTED]:10025, delay=21, delays=0.71/0.02/20/0, dsn=5.6.7, status=bounced (SMTPUTF8 is required, but was not offered by host content-filter.redacted.net[REDACTED])
I know that Postfix does support UTF-8 by default and in fact is able to receive the message. I can't find any documentation regarding UTF-8 support on Apache James side, or how to configure it.
AFAIK Postfix can't automatically translate UTF-8 to punycode, so I'm really puzzled how can I make it work.