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I am at my wits end.... I have a product on Server A that uses SMTP to send notifications to end users. Server B is the exchange server. I can telnet on port 25 from Server A to Server B but cannot telnet from server B to Server A on port 25. Does this mean port 25 is open on Server A to send but not receive? If so how can I open the port without utilizing Windows Security Configuration Wizard? Or is my thought process all screwed up here? Any help would be greatly appreciated! I am sure it is easy and I am just living in Friday afternoon already.

Thanks!

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Last Post by DimaYasny
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On the PC your having issues with, open up the command prompt (Start > run > type cmd then click ok.

ping the server's smtp address e.g type: ping mail.yourserver.com then press enter.

If it fails, your ports are not open.

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On the PC your having issues with, open up the command prompt (Start > run > type cmd then click ok.

ping the server's smtp address e.g type: ping mail.yourserver.com then press enter.

If it fails, your ports are not open.

ping does NOT test port 25, it tests ICMP connectivity.

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As for the issue, on server A, the product, is it a full fledged SMTP server, or does it simply initiate a scripted SMTP session when it needs to? because if it does, you will not be able to aconnect to it by port 25, since it doesn't have a daemon that would listen on port 25.

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It would still try to access the mail server.

OK, to test port 25, use a Telnet Session. Press Start > Run > type telnet and click ok.

Type: telnet yourservername.com 25

For example, type: telnet mail.danyweb.com 25

You can also use the servers IP address or the FQDN instead of the hostname.

telnet 192.168.1.1 25 (replace with your servers IP)

If it works you should see a responce like:

220 yourserver.com Microsoft Exchange Internet Mail Connector <version number of the IMC> (if your using Microsoft Exchange).

If it fails it will tell you that also.

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It would still try to access the mail server.

it will try to see if it's alive by the means of an ICMP echo request. Whether server A is alive i snot an issue here.

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many mailing (and not only mail) daemons work by demand only, so they wait, without listening on a port, get woken up by a software's request to send an email, and go back to sleep once they finish.
having said all that, it is easy enough to send an email without havinf a mail server

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