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Remote users can't find mail server

By pbtoms ·
Our email works fine, we can send and receive from this office with Exchange (5.5). However, when I try to check mail from home, or when our other two offices try, they get a "not found" error. This started this past weekend, after a power outage. Here's our setup...
SBS 4.5 (NT 4 and Exchange 5.5). This connects to another server running NT 4 and Proxy, which in turn connects to a SonicWall Soho2 firewall, which is connected to the DSL bridge. The firewall is set to send POP3 and SMTP requests to the proxy server, which passes them on to Exchange. Worked fine until this weekend. We can access the internet, and send and receive email with no problem, just can't seem to connect to the mail server from outside. Any ideas?

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Remote users can't find mail server

by duwaned In reply to Remote users can't find m ...

Hi.

To make a more accurate diagnosis, I would require more info, but I will give it a go...

When you say you can't access your mail server externally, are you talking about OWA, POP, VPN or what? The fact that you had a power outage is the key here though.

1)Have you checked that all you network devices (Firewall & DSL) have kept their config? Maybe the entries to forward SMTP, POP3, etc to the Proxy were not saved after being added, and subsequent to the power outage have been lost?

2)Are all the Proxy services, and IIS services running on your Proxy server? Maybe one of them never came up properly after the power outage?

3) Can you contact (maybe ping depending on Proxy setup) the Exchange server from the segment betweenthe firewall and the proxy?

Have a look at these, and let me know. I am sure its something simple!

Hope this helps.
Regards.
Duwane

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Remote users can't find mail server

by duwaned In reply to Remote users can't find m ...

I don't think that you have any DNS issues as suggested below, as I can resolve your servers name from my end, but cannot get a reply from a ping. This is not necessarily a problem, as it could be your ISP, your firewall, or your Proxy server (packet filtering) that is stopping pings.

Do you have any Network Address Translation (NAT) running on your firewall or DSL? If this is the case, then someone mave have stopped the Proxy from IP forwarding? Do you have packet filtering enabled on your proxy? If not, try to allow packet forwarding as a test. Then get your clients to try to attach again.

Also check that your DSL has not lost its config (if configurable) as it normally needs pinholes for the POP3 ports to allow incoming connections. Let me know how it goes.

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Remote users can't find mail server

by pbtoms In reply to Remote users can't find m ...

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Remote users can't find mail server

by pbtoms In reply to Remote users can't find m ...

It's POP3, using Outlook and/or Outlook Express. They say they can't find the server (mail.regrizlaw.com). The firewall config is still there. Proxy services appear to be running. Proxy server can ping Exchange server. Somewhere there must be some other POP3-related setting that got screwed up, I just can't figure out where it would be!

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Remote users can't find mail server

by Stillatit In reply to Remote users can't find m ...

Reminder - the number 1 troubleshooting question is always "What changed?"

My guess is that nameservices broke somewhere. You can test this by trying to ping from the client to the mail server name. If the ping command returns the correct address, this is not the problem. If not, look at DNS, or insert a hosts file or LMHOSTS file entry.

If you find your server, check that the firewall is still allowing ports 110 and 25, and forwarding to port numbers still is turned on and working in the firewall. You can do this (for port 25 anyway) by using telnet from the client:
telnet <servername> 25
If you don't get an smtp greeting message back, you are not connecting.

Good luck.

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Remote users can't find mail server

by pbtoms In reply to Remote users can't find m ...

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Remote users can't find mail server

by pbtoms In reply to Remote users can't find m ...

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