Hi, My public IP-address has changed. Receiving email is no problem, but now everyone who wants to send an email (Outlook, OWA) gets an error: Relaying denied. IP name lookup failed ([new-public-ip-address]). Any help is welcome, thanks for your time and help! Gerard

Hi, How is your mail delivered to the internet? Through a smart-host - if yes you need to configure the smart-host to accept mails from the new IP address. Did you also change the IP address of your PTR record (in public DNS)? Leif

Hi Gerard, Does your new public IP has reverse DNS lookup set (PTR record) with your ISP? Check and make sure that it resolve the nslookup query.

Turned out to be a problem by the ISP (never had a reverse set for my public IP address..., it turns out you don't need it(?!)). Thanks for all the help - not able to send mail is quite stressy these days. Gerard

Hi, Sure you need a PTR record. Some mail servers check for a PTR record and won't accept mails if none is found. Leif

Hello Leif, Thanks for your help! Well the "funny" thing is that since this weekend we sometimes(!?) can send emails. We don't have a PTR for the old public ip-address and we don't have one for the new one either. But like to make one if this solves our troubles! If our public ip-address is 98.76.65.43 what do we need to create? Exchange (2003) runs on our domain server (win2003) and the only PTR we have in the only reverse lookup zone we got (192.168.1.x subnet) and is called "192.168.1.7 Pointer(PTR) domsrvr.ourdomain.org". Guess this has been automatically created making the host record for the domain server. Any help is welcome! Gerard

It seems you are getting relay errors from your exchange server, is that correct? have you verified it from headers or bouncebacks? As more and more organizations rely on anti-spam technologies, it is very important to have correct PTR records in place, however, not having one in place should not cause your server to reject your messages with relay error. This usually will happen on recipient servers and you will get bounce backs if that happens (from outside servers), or depending on how recipient servers are configured, there may be no bounce back at all. I think you should concentrate on checking all exchange configuration including SMTP configuration for relay and see if there are any IP restrictions that could be causing this.

Hello Bhargav, Thanks for your help!! We got the following kind of bounced messages (sometimes emails can be sent without any problem): Reporting-MTA: dns; domsrvr.ourdomain.org Final-Recipient: RFC822; test@recipient.com Action: failedStatus: 5.7.1X-Supplementary-Info: <domsrvr.ourdomain.org #5.7.1 smtp;550 5.7.1 <test@recipient.com>... Relaying denied. IP name lookup failed [98.76.54.32]>X-Display-Name: Test There are some Relay Restrictions; only the ISP is allowed to use the system our public ip-address is not listed (adding this address doesn't help). We hope you can pin down this problem. Thanks, Gerard

Do you have any firewalls between your exchange and outbound? Is the following correct? Outlook/OWA -> Exchange (domserver) -> Internet? or does it look more like Outlook/OWA -> Exchange (domserver) -> Firewall ->Internet? Which firewall do you have (if any). Questions below applies if you have a firewall. Does the firewall use ACLs? Does it use DNS resolution? What DNS server does it use? Canthat DNS server resolve PTR record for the IP 98.76.54.32 It does come down to having a correct PTR. You should ensure you have PTR for that IP on any DNS server that your environment can refer to. It either should authoritatively resolve the PTR record (i.e. have the reverse look up zone for that IP) or should be able to resolve via recursion. This may also mean clearing your DNS cache on all servers that belong to exchange routing and are under your control. When I did PTR lookup on your IP I got the following: No host name is associated with this IP address or no reverse lookup is configured. Can you have the PTR record created correctly by your ISP? Thanks, Bhargav

Hi Bhargav, Thanks for your help!! The firewall is switched off, still we got these problems (though it sometimes works). DIG DNS lookup gives us (note 98.76.54.32 is just an address (not ours (firewall off))):; <<>> DiG 9.3.2 <<>> @localhost ourdomain.org A ; (2 servers found) ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 38341 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0;; QUESTION SECTION: ; ourdomain.org. IN A;; ANSWER SECTION: ourdomain.org. 86398 IN A 98.76.54.32 ;; Query time: 0 msec ;; SERVER: 127.0.0.1#53(127.0.0.1) ;; WHEN: Wed Oct 8 09:15:17 2008 ;; MSG SIZE rcvd: 43You are coming from IP address 98.76.54.32 using port 60897. A DNS reverse lookup on this IP address does not work. Any idea how to solve this? How to make the reverse lookup working (do we need it)? Thanks, Gerard

98.76.54.32 is your address as the DIG DNS says "You are coming from IP address 98.76.54.32 using port 60897" Your ISP might be managing reverse DNS for IP pool. Contact ISP and have them create reverse lookup for this IP and point it to correct servername (publicmail server namefor your domain).