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Hi all,

It has been asked to deploy a Kerio Connect backup server with higher MX.

I would like to use ETRN to sync mails back to primary but I have an error :
Cannot connect to SMTP server "My MX 20" (ETRN download)

When I created it, it was on same network and worked fine.
Now it is remote site but fail. Port are fine, SMTP is fine too on MX20.

What's wrong with the setup ?

The company is asking me to find a new system but I want to have this working .. it worked locally ...

Pavel Dobry (Kerio)

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Can you telnet on that backup MX server to port 25? Does it respond? It is probably a firewall issue or blocked SMTP connection.

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Hi Pavel,

it does not work even locally from server telnet localhost 25 is not reaching ...
it is very strange.

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Are you sure the server is listening on port 25? On Linux you could try netstat -ltp to list processes and commands listening for tcp connections. On Apple and Windows there should be similar commands.
You should also check for access restrictions in Connect.

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Hi, I found the issue.
Port 25 is captured by another SMTP services for an inhouse application.
Kerio is hosted on same server that this application.
MX20 is setup to use this SMTP for outgoing mails in Kerio.

Is it possible to change the SMTP port for ETNR or to force ETNR with SMTP Sec 465 ?

Telnet on 465 is working to Mx20

[Updated on: Thu, 04 December 2014 12:45]


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Looks like a bad layout too me.

ETRN works different then you think. The kerioserver asks the ETRN Server if there are any mails. If yes, the ETRN Server connects to the kerioserver with smtp and delivers the mails. Kerio does not download the mails!

That means you a) have to change the SMTP Port for Kerio and b) tell your ETRN Server which port he has to use to deliver the mails to kerio.

What I don't get is this inhouse stuff. IS the inhouse mail server app on port 25 the one receiving the mails from the internet? Or Kerio? How does it work exactly? Mind to tell us your setup a bit more in detail?
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