what's wrong with FreeBSD mailserver (cannot send PR via send-pr)?

[Anton Karpov]

I've made a new port and, as usual, fulfilled a send-pr form. but this is in
my logfiles:

Mar 23 15:04:11 mercury postfix/smtp[97493]: 8BE1678CA4: to=<
FreeBSD-gnats-submit at freebsd.org>, relay=mx1.freebsd.org[69.147.83.52]:25,
delay=4.3, delays=0.02/0.02/3.7/0.63, dsn=4.7.1, status=deferred (host
mx1.freebsd.org[69.147.83.52] said: 450 4.7.1 <
FreeBSD-gnats-submit at freebsd.org>: Recipient address rejected: Service is
unavailable (in reply to RCPT TO command))

Looks like mx1.freebsd.org don't like emails to FreeBSD-gnats-submit@

Any comments?

ps; please DO CC me, as I'm NOT subscribed to this list