Posting gives me bounce messages from MAILER-DAEMON@nim-lang.org
Contained error message from nim-dev@freelists.org (forum mirror?):

<nim-dev@freelists.org>: host turing.freelists.org[206.53.239.180] said: 450
    4.7.1 Client host rejected: cannot find your hostname, [178.62.143.63] (in
    reply to RCPT TO command)

Since 178.62.143.63 is nim-lang.org, this looks as if freelists.org chokes on forum-generated mails.
Probably related to #93.