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SMTP/Reverse DNS-Exchange problems

I have Exchange 2003 and appear to be having reverse DNS lookup problems or possibly SMTP configuration issues. We can send email to any destination when we have a smart host specified in SMTP properties but experience return emails from specific destinations (ex. hotmail accts) when not using a smart host.

I want to permanently remove the smart host setting but cannot until I resolve the issue.

note: when not using smart host: return emails specify our local domain mail.gcps.local verses mail.greensville.k12.va.us which we are suppose to see.

Thanks

marc_nivens

It sounds like your IP is blocked by the receiving servers for some reason (probably open relay). Going through a smarthost will bypass this since they receive the mail from a different IP. Go to http://www.ordb.org/lookup/ and search for your IP to make sure you're not listed as an open relay.

If thats not it, can you tell us the text of the NDR?

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grblades

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mtmor

ASKER

Iv'e already checked the blacklist sites and no signs of this being the problem, IP is fixed and DNS reverse lookup appears to work fine.

However, It appears the firewall (router) was causing the problem...Thanks anyway!

prav007

Some websites the best example aol.com does not accept mails from mail servers which do not have reverse dns lookups configured for their ip addresses.

Might be your firewall is natting the ip address and there was a problem with NAT .

At one site I had faced such a problem and found out that the ISP was supposed to make a reverse dns entry for a company since they had hosted their dns servers at the ISP. Once this was done the problem vanished . The other solution is to use the ISP's SMTP server as a smart host . However in this case u r totally dependent on the ISP.

Best Regards,
Praveen