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Newbie: XS Does not receive mail anymore, what to do?

Posted on 2001-08-31
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Last Modified: 2006-11-17
Hi all,

Maybe this is easy, maybe not, but it definitely is urgent. My network admin quit and now I face the following problem: XS (5.5 SP3) does not receive any mail anymore. It does send mail, it sends mail between it's own users on it's (only) site and server, but no mail is received in the mailboxes.

Except from creating new users and doing some configuration with the books nearby, I know little of troubleshooting XS. My system is configured to have its own site and it has one server connected to it. No fancy stuff, only a bunch of users in one domain. No trusts, no relaying, no limits, just easy as can be (I think). To narrow the problem I have turned off any firewall/proxy.

Where do I start to trace down the problem? How do I know that my ISP is sincere when he says that their configuration is correct? How do I trace a message to (or through) my server? How do the diagnostics loggings work?

I know, only one q. is allowed. So, I'm satisfied with any answer that gives me back my mail.

Rgds,
Abel
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Question by:abel
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slink9 earned 100 total points
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by:abel
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Thanks.
I've read quite a lot by now, but I still haven't found the solution. But I may have found the error, or at least what is causing the problems, it seems to be outside XS.

On http://www.symantec.com/securitycheck/ it is possible to check the security of the system. It also includes a port scan (only the major ports are scanned) that can be clicked on after the check is done (you find it under Network Vulnerability Scan -> details). This port scan revealed that port 25, 119 and 1080 were all "stealth", which means: they don't "exist" on my system, as if a firewall blocks them. It is not closed, it doesn't respond to port probes at all! To me this seems pretty weird on a system that runs SMTP.

I don't know how XS shows its ports, but I guess that it should at least show them as being "open". Maybe the Norton check is erroneous, but actually I don't think so. Other issues that point that way are: I cannot connect to port 25 from anywhere outside using telnet, yet my server responds to things like pinging. Btw, I can telnet and send mail from inside the domain. To me that indicates that the IMS is running correctly, and that the problem lies elsewhere.

Can someone scan my SMTP port? What can be the matter with it? I haven't changed the configuration, I haven't installed a firewall, virus-scans from different vendors don't reveal anything and quitting most of the running services doesn't unblock the ports. The IP-address of my server is 143.84.55.142. Please be a bit polite with it, I currently - due to these problems - don't run a firewall.

Does anyone know of a way to determine what program is blocking this port? Is it possible that this is blocked from outside my server? Any other possibilities?

Rgds,
Abel
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by:slink9
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That was not a good idea.  There are too many bored teenagers out there who will now have a "leg-up" on breaking into your system.  You may want to submit a request to CS (link at left) and ask that they edit out your IP address.
I have all of my ports running as stealth but my mail works fine.  Since you seem to be downloading mail (or attempting, at least) from an ISP, the ports should not matter.  The mail is requested from inside and is sent because of that request.  Are you using SMTP mail?  If so, disregard this.
What kind of router do you have?  Is the router somehow blocking the mail?  My stealth ports are controlled by the router configuration.  I ran the port scan at www.grc.com and it showed that nothing can get into my network through the router.  Check the router configuration and see if there is something there that can cause this.
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by:abel
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You're right, I wasn't thinking. So I turn on the firewall again, just to be sure.

I am directly connected to the internet with an ADSL modem, I do not have a router. I do not get forwarded mail, the MX records point to my ip address. I use SMTP mail because I think that's needed to run mail and to be able to receive and send mail. But if I don't need that, even better. But isn't the IMS using SMTP?

The port scan you ran is the one from Norton? At least it means that I don't have to open the SMTP port, or do I, because I run mail directly?
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by:slink9
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You are running SMTP so I would expect that port to need to be open.  Does the modem have built-in security features?
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by:abel
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No, except for a routing table, which is configured for every address on every port to be passed through, except for some special addresses (like the broadcasting address and such). Do you have any idea on how I could determine what program blocks this address? Is it possible to block it from outside my computer and if so, how do I determine that?
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by:abel
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All our trouble appears to have been in vain. It is the ISP after all, they have informed me incorrectly about the configuration and about them blocking my port 25. This easily explains the whole issue.

What todo with the points now that I have given the answer myself? Shall I delete the question? Or shall I reward them to you for you trouble? Let me know what you'd find reasonable.

Rgds,
Abel
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by:slink9
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Whatever you think is best.  If the links and info I provided helped in some other way, then accept one of the comments as an answer.  If they didn't, don't delete the question, there is good info here that may help someone else.  You can click on the CS link (at the left) and put a link to this question and ask them to reduce the points and PAQ it for others to view.
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by:Computer101
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As requested by abel, points reduced to 100 to award slink9.

Thank you
Computer101
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by:abel
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Thanks for your help.

To anybody that bought this question: in the links is some basic material for troubleshooting IMS and other parts of exchange server.
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