Dear all,

I have been using freebsd 5.4 for 2 months using fetchmail to retrieve mails and using sendmail to send mails.
I have no problem with fetchmail to retrieve mails from pop3 server.
And most of the time I have no problem with sendmail.
But recently I found that I could not send mails to freebsd-stable@freebsd.org.
Actually sendmail is a mail server (not a client), which sends mails directly from my host to other mail servers without relaying and SMTP is a server-to-server protocol, which requires reverse DNS to gain full functionality.
Correct me, if I'm wrong.
I found that rDNS was not supported to the given IP address and PTR record was not found (I don't know so much about them).
So my sendmail can not work with some destination servers.
How to config rDNS? Shall I call ISP?
Does relay help me solve this problem? And how to config it?

More info: I'm on dual stack; dynamic IPv4 and static IPv6 (6bone).
Somebody who experienced this problem please point me out.

Thanks in advance,
Jaguar