I'm having a problem sending e-mails through Microsoft Exchange to a specific destination. I know that the destination e-mail address is correct as other people in different organisations have used it successfully. The error message I get is as shown below. The IP address shown is my fixed ip address. 7.mx.freenet.de #550 inconsistent or no DNS PTR record for 78.33.224.69 (see RFC 1912 2.1) ## Any ideas how I can fix this? Thanks

LionKingLeo, It looks like you may not have a reverse DNS record for your email system. Because the reverse lookup zone for 78.33.224.69 is with your ISP they are the authoritive DNS server for that IP address. You can call them and ask them to create a reverse dns record or "pointer" that maps 78.33.224.69 to the DNS A record for your email system. Some people use mail.myorg.com for the A record for mail that points to the email system. To verify what the A record is you can go to mxtoolbox.com and do a MX lookup for your email domain. This will list an A record that the MX record resolves to. Your current PTR: http://mxtoolbox.com/SuperTool.aspx?action=ptr%3a78.33.224.69 When it is fixed this lookup will show mail.myorg.com or whatever A record name other than mail you are using. In my case I actually use webmail.myorg.com for the A record that the MX record points to. http://technet.microsoft.com/en-us/library/cc784493(WS.10).aspx Also some research shows if you have a CNAME record for the webmail and that CNAME record is used with the MX record than you could get a message similar to this. You should have "mx -- > a --> IP Address" for a forward lookup and "ptr --> a" for a reverse lookup. Jon

The error says PTR record is not there - some domains check for PTR record before accepting mails from other Org. For every SMTP server or Exchange Server computer that sends outgoing Internet e-mail, make sure that there is a valid PTR record for the Public IP address of that sending SMTP server or Exchange Server computer. This may be a firewall, a router, or another device that used to publish your domain information to an IP address that is visible by Internet hosts. For example, your Exchange Server computer is behind a firewall with an internal IP of 10.10.10.1, and the firewall has an external IP of 4.3.2.1. When the Exchange Server computer sends e-mail to <var>source.com</var>domain through the firewall, the receiving mail server sees that the 4.3.2.1 IP address is connecting for SMTP Communication. The receiving e-mail server performs a reverse DNS lookup against this IP address, not necessarily the MX record. The e-mail server must find a PTR for 4.3.2.1 pointing to a valid host record in the <var>source.com</var> domain.Best Rgds, Ashish | Unified Comunication | MCTS | MCITP | Please remember to select option "Propose As Answer" if solution work for you | My posts hold no assurances, no promises, and they measured no rights.