email bounces back with 550-verification error
Posted on 2006-05-30
We are using Windows 2003 Small Business Server with Exchange. We have a static IP address for our mail server which is hosted by IX Webhosting. The problem is that some of our emails bounceback with the following message:
The following recipient(s) could not be reached:
John Doe on 5/9/2006 11:06 AM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<myserver.mydomain.local #5.5.0 smtp;550-Verification failed for <firstname.lastname@example.org>>.
All of my research points to errors in the DNS configuration which is configured at IX Webhosting. However, when I call them for Technical Support they tell me that there isn't a problem with the DNS configuration, but with Outlook. I can't find any problems on the server or with Outlook. But when I go to DNSreport.com and enter our domain the following two tests fail.
OPEN DNS Servers ERROR: One or more of your nameservers reports that it is an open DNS server. This usually means that anyone in the world can query it for domains it is not authoritative for (it is possible that the DNS server advertises that it does recursive lookups when it does not, but that shouldn't happen). This can cause an excessive load on your DNS server. Also, it is strongly discouraged to have a DNS server be both authoritative for your domain and be recursive (even if it is not open), due to the potential for cache poisoning (with no recursion, there is no cache, and it is impossible to poison it). Also, the bad guys could use your DNS server as part of an attack, by forging their IP address. Problem record(s) are:
MX is hostname not IP. ERROR: You have one or more MX record(s) that contain an IP address. This is not valid. A fully RFC-compliant mailserver will not be able to send you mail (although some mail servers will, due to the TCP/IP functions that they use). The problem MX records are:
I added an MX Record that referred to the A record instead of an IP address, but it did not help my problem.
Any help is appreciated!!!