Your DNS settings seemed to be correct.
Check once again your mail server logs. I think that it's working now.
I successfully sent email to postmaster@thesecond.org from mine.
See the log:
postfix/smtp[29426]: B3E3F1A21A57: to=<postmaster@thesecond.org>, relay=mail.thesecond.org[192.34.62.191]:25, delay=2.1, delays=0.14/0.01/0.32/1.6, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as 9C39060D23)
Also I advise to use following service http://www.intodns.com/. Here you can check your dns records to find out where the problem is ( if the problem related to dns 
).