Archived from groups: microsoft.public.exchange2000.general,microsoft.public.win2000.dns (
More info?)
Thx for your input guys much apprecitaed.
I will get in contact with my isp to see whteher reverse loookup is
something we can have on the IP address.
thx again.
"ObiWan" <obiwan@mvps.org> wrote in message
news:uvfTp3bvEHA.1292@TK2MSFTNGP10.phx.gbl...
> <snippage>
> > What cause of action should I take to fix the
> > delivery failures, what options do I have, thx.
>
> To explain it in "clear"; let's assume you own
> the domain "foobar.com" and you have a mail
> server "mail.foobar.com" which is the primary
> MX for the domain; this server has an address
> of 1.2.3.4; now
>
> some mail servers perform a reverse lookup
> on the incoming connections and check if the
> "helo" string matches the reverse DNS name
> this means that if your server connects to the
> SMTP server ad 5.6.7.8 and starts an SMTP
> session it will send out something like
>
> HELO mail.foobar.com
>
> now, the server at 5.6.7.8 has the "reverse DNS
> lookup" enabled, so it will issue a reverse lookup
> for 4.3.2.1.in-addr.arpa; at this point, if the DNS for
> foobar.com is correctly configured the answer to
> such a query should be
>
> mail.foobar.com
>
> it that's not true, the mailserver at 5.6.7.8 will just
> refuse any mail from your server at 1.2.3.4 since
> the HELO id-string doesn't match the reverse DNS
> lookup result
>
> to solve this issue; given you don't own the IP block
> 1.2.3.x you should talk to your ISP or carrier and ask
> them to create an entry in their DNS for your mailserver
> so that 4.3.2.1.in-addr.arpa will resolve to mail.foobar.com
> on the other side, if you own the IP block it will be just a
> matter of creating the correct entry into the reverse zone
>
> hope it's clear; if not, feel free to ask
>
> Regards
>
>
> --
>
> * ObiWan
>
> Microsoft MVP: Windows Server - Networking
>
http://mvp.support.microsoft.com
>
http://italy.mvps.org
>
>