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What is the problem - MS Exchange or ISP

By 262noni ·
We're using MS Exchange 5.5 server for our emails and a dedicated dial-up connection for our internet access. Just 2 days ago, we stopped receiving emails from outside our network. We are able to send emails to some domains such as hotmail.com or yahoo.com but other domains will reject our emails with this message: "sender address unknown" or "Host unknown". For rejected outbound emails the error message would be "DNS failure". If one would send us an e-mail through yahoo, for example, he'll get "sorry could not find the host" message.

Today the server received inbound internet mails, but the address includes the domain name and server name. So instead of @domain_name it is @server_name.domain_name. Since this is not the domain name configured in our MS Exchange, the emails would not go into the proper mailboxes. So, I rerouted all @server_name.domain_name emails to @domain_name. This worked in getting our e-mails into the proper mailboxes but our e-mail addresses will have to use the @server_name.domain_name format, and I don't think that's the way to go. This is true also for outbound mails. If I insert the server name in the email address, it'll get through, otherwise I'd get a "DNS failure" message.

Our domain name server is with our ISP but they say there is no problem at their end and insists that our MS Exchange is causing the problem. When I ping our domain_name I do not get a reply, when I ping server_name.domain_name I do.

Anybody knows what's happening and how to solve this? If MS Exchange is the problem, how can I correct it. If the problem is with the ISP where do I tell them to look?

If you need more information, you may contact me through ncerillo@hotmail.com

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What is the problem - MS Exchange or ISP

by sgt_shultz In reply to What is the problem - MS ...

2 cents: you are using ISDN? can you reset the router?

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What is the problem - MS Exchange or ISP

by 262noni In reply to What is the problem - MS ...

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What is the problem - MS Exchange or ISP

by 262noni In reply to What is the problem - MS ...

Thanks, anyway.

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What is the problem - MS Exchange or ISP

by smoothe In reply to What is the problem - MS ...

You are talkign about two completely separate issues (possible caused by a bad or many bad DNS entries....but). Try doing an NSLOOKUP for the MX records on yourself, and verify that those servers respond on port 25. IF they do, how does that mail get to you, directly? reroute? ETRN?

Then, for outbound do NSLOOKUP's for those domains (ie yahoo.com) against your ISP's dns servers (the ones that are configured on Exchange I presume if you're using DNS for delivery.

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What is the problem - MS Exchange or ISP

by 262noni In reply to What is the problem - MS ...

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What is the problem - MS Exchange or ISP

by 262noni In reply to What is the problem - MS ...

Thanks, anyway.

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by 262noni In reply to What is the problem - MS ...

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