Hi all, I have MS EX server 2003. Now what i am facing is that , one of the customers of my users is sending the email to us. But we didn't receive that customer email.When the customer sending email to us, they receive bounce mail with below error. " Router : Failed to connect to SMTP host "organization's name , (example.com) " because : the remote server is not a known tcp/ip host " But the other customers , meaning other companies , can send to us.Only that customer ,company cannot send to us.But they can send sometimes ,but sometimes cannot send . Anybody has any idea, ????? What may cause that problem . I am also headache for that issue , Please advise , if anyone know. Thanks

Hi, Any reason why you think that the problem is in your end of the communication? Did you takt to the mail admins in the remote company and ask them to troubleshoot. The problem could very well be in their end. Have them produce a SMTP log shwing that their server is trying to connect to your server. Leif

Hi, From your description, it is possible that the issue is from the customer. And you can check the following reasons: 1. Check whether the network is stable. 2. The external Domain Name System server for your domain must have mail exchanger resource records pointing to your mail servers. So please check. Hope this helps. Thanks Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.