RE: Mail error: reason: 550 5.0.0 You must use a valid mail serve r

From: Cowles, Steve (steve_at_stevecowles.com)
Date: 11/16/03

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    To: "'redhat-list@redhat.com'" <redhat-list@redhat.com>
Date: Sun, 16 Nov 2003 13:39:40 -0600

    Mike Vanecek wrote:
    > Two questions.
    >
    > 1. Why do I not run into the same reverse lookup problem? Is it
    > because I have a static ip?

    Probably. FWIW: I have a static IP address through Verizon and never had a
    problem deliving e-mail even though reverse lookup queries did not match the
    name lookup. After three years, I finally found the right department at
    Verizon and got my PTR record changed.

    >
    > 2. If I understand things correctly ... The only way host ip-address
    > will return my domain-name is for my isp to put a PTR record in their
    > zone definitions (which most are reluctant to do)? Any other way to
    > get a reverse lookup to point to my domain name as opposed to the isp
    > name?

    Not that I'm aware of. Your ISP has to either:

    1) Delegate the PTR record lookup at your DNS server.

    2) Change the PTR record to what you specify in their zone files. This is
    what Verizon did for me. They would not delegate (add a NS record) to my DNS
    server. BTW: Based on my conversations with Verizon, they only make these
    PTR record changes for Business (static) accounts, not residential (DHCP
    assigned) accounts.

    If you want to understand why your ISP must make the PTR record change...

    Type: dig +trace -x yy.yy.yy.yy

    where yy.yy.yy.yy is your static IP address. The above dig command will
    follow the query back from the root name servers. The final "answer" should
    come from your ISP's name servers.

    Steve Cowles 

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