550 5.7.1 relaying denied - IP name lookup failed

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pc00830

All our users have a problem to send mail to earthlink.net
and get undeliverable message like this:
<mail.ourserver.com #5.7.1 smtp;550 5.7.1
<[email protected]>... Relaying denied. IP name lookup
failed (x.x.x.x).

When using nslookup to query earthlink.net, I got DNS
request timed out. timeout was 2 seconds.

There are not errors in Event Viewer. Any suggestions?
 
is yours a public dns server? do you have a reverse lookup zone? sometimes
when sending mail, a reverse-lookup will be performed on the sending domain,
and if there is no reverse lookup zone configured, the mail server will deny
the mail/relay.

Dan
 
Dan,

Thank you for the help. We are using internal DNS and do
have a reverse lookup zone. For the test, I ping the
excahnge server name and ip, both reply. any other
suggestions?
 
quoted from http://www.ChicagoTech.net
DNS request time out - ip name lookup failed When troubleshooting Outlook
550 5.7.1 relaying denied - ip name lookup failed by using nslookup to
resolve host name, you may receive "DNS request time out...*** Request to
mail.chicagotech.net time-out. Possible causes: 1. Incorrect DNS settings.2.
Incorrect TCP/IP settings on the DC.3. Missing PRT on Reverse Lookup Zones.
--
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Posting on MS newsgroup will benefit all readers and you may get more help.

Robert Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN, Anti-Virus, Tips & Troubleshooting on
http://www.ChicagoTech.net
This posting is provided "AS IS" with no warranties.
 
Is it just one domain?? Why don’t you use a DNS forwarder to point to an ISP DNS server for instance? You can do this in two ways: either open DNS right click your Server select properties select the forwarder tab and enter an IP address of your ISP DNS. Or if you use Exchange (depending on version) select administrative groups / first storage groups/servers. Your server name/protocol/smtp right click default SMTP virtual server select deliver tab /advanced and then click configure

What happens if you go to nslookup and type

Set qt=m

Type the domain name ..
 
In
pc00830 said:
All our users have a problem to send mail to earthlink.net
and get undeliverable message like this:
<mail.ourserver.com #5.7.1 smtp;550 5.7.1
<[email protected]>... Relaying denied. IP name lookup
failed (x.x.x.x).

When using nslookup to query earthlink.net, I got DNS
request timed out. timeout was 2 seconds.

There are not errors in Event Viewer. Any suggestions?
Click to expand...

THis is a relay denied message meaning that your users cannot send mail. But
the way you're getting the "IP name lookup failed" kind of means that a
reverse lookup on your IP is not coming back to your mail server's MX
record. You'll have to contact your ISP to create a PTR record for your mail
server's IP address since they own the IP block and it's reg'd to them.

Many orgs out there now check reverse DNS as the first attempt to stop UCE.

--
Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS-IS" with no warranties and confers no
rights.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory

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