Small Business Networking
Subscribe to this site with RSS
Problems sending e-mail to one particular company
Several days ago, my company started having problems sending e-mail to just one particular company. We are getting either
NDR (Non Delivery notices) or a message indicating that the message has been delayed in delivery. I have been talking with
the e-mail admin at the other company and they are getting all the messages we send. They aren't seeing any of the errors
that we are. So far it is just the one company but I am concerned that this could grow into problems with more companies.
Any idea of how to figure out the cause of the problem?
-- Via the Internet
Since the problem seems to be isolated to just one company, that makes the answer a little easier to find. I would start out by putting some type of protocol analyzer between your firewall and the router connecting you to the Internet. Setup a capture filter that watches the e-mail server at the other end and the DNS servers that the other company is using. You may need to expand this capture filter depending on what you find but this will get you started. Let the protocol analyzer run for several hours depending on the amount of e-mail traffic going between the two companies.
Look at the exchange of traffic between you and the other company to see if anything looks strange. If nothing shows up, compare this capture with a capture of a similar type with another company to see if you find any differences.
The next thing to look at is your DNS servers. If you aren't running your own external DNS servers, look at the DNS servers that hold the authoritative information for your company's Internet domain name. There are two tools that I use when looking into this kind of problem - nslookup and dig.
Nslookup gives me quick feedback with minimal command line options. The tradeoff is that where there are problems in resolution, the only error you may get is DNS Server Timeout. This is where Dig gives you a little more to work with. In the command line versions I have worked with, the error reporting when there is a problem is a little more descriptive in most cases. If you aren't running linux at your location, you can find both gui and command line versions of Dig that should help you. I prefer the command line option as those seem to give overall better information from the various implementations I have worked with as compared to gui versions of the tool.
| Use this form to start a public discussion with other Linux World users on this article. Log In | Register for an account (Why you should) |
Note: Register to have your user name appear; otherwise your comment will show up as "Anonymous."
*Anonymous comments will only appear once they are approved by the moderator.
• Dell puts Linux and Atom in Vostro PCs
• Mozilla names best Firefox 3 add-ons
• Torvalds: Fed up with the 'security circus'
• Dell Latitude ON - big win for Linux
• Open source advocates hail appeals court ruling
LinuxWorld Conference and Expo San Francisco, August 4-7, 2008.
Linux Plumbers Conference Portland, OR, Sept. 16-19, 2008.
FreedomHEC Santa Monica, November 8-9, 2008.
Featured Whitepapers