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Hello, aloha, ahoi and that kinda stuff... glad to see that Kerio actually has a forum, actually.

Currently one of our facilities is running a Kerio Connect + Kerio Control solution, which is kinda creepy. I've been sending various employees there to fix the enourmous problems that are occuring. Don`t ask - it`s been built by the most competent guys.

So this facility will be running around 5 more years(or at least this is the contract). We have rebuilt the entire inside network in the proper way, including the backup lines and the wireless coverage(on over 52 000 sq. meters, this was annoying, oh gosh).

And now we have this forgotten from god server with Kerio Control. Okey, not so bad. And adding up on it a Kerio Connect on another server, the same network. So here the issues begin...

So here is the setup:

Router( on full DMZ to

Kerio Control server(Win Serv 2008R2 SP2), on plus
Forwarding to on SMTP, SMTP Secure, SMTP submission, POP3, POP3 Secure, IMAP(and the whole other stuff which is mail related).

Kerio Connect server(Win Serv 2003), on plus


Form the inside network you can work pefectely.

From the outside network you can run Outlook IMAP acc(for example ports 143 in/25 out). You can view and recieve mail. But you cannot send mail, recieving the error:

Task 'admin<_at_> - Sending' reported error (0x80042109) : 'Outlook cannot connect to your outgoing (SMTP) e-mail server. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).'

"admin<_at_>" - replaced on purpose. Message stays stuck in "Outbox".

If you actually access the web interface, everything works - you can send and recieve. As far as the logs on Kerio Control show - nothing has been blocked. Kerio Connect is not reporting problems related to this in the logs. Router has firewalls down and the DMZ up. Port checking is showing all related ports open(e.g. 25, 143, 389, 587, 636, 993 etc).

I could really use a hint on this, else I shuold schedule a server mirgation to a trustworthy platform with actual support and actually lead the whole circus, which is not one of my favourite things to do.

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From the machine with the Outlook client, can you telnet to port 25 on the Kerio Connect server?

Also, if you allow Secure SMTP, I would rather connect to port 465 (Secure SMTP) or 587 (SMTP Submission) with Outlook instead of using port 25.

Dexion AG - The Blackberry Specialists in Switzerland

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Nop, telnet to port 25 fails.

I have actually tried some topology chagnes and redirects on router level. Nothing seems to help, it is only getting worse(for example, cannot recieve mail and cannot send mail). The old setup allows recieving, but not sending.

This is weird, because IMAP(143) is getting routed properly(you can recieve mail outside the network). Ports 25/465/587 are in the same group(routed by the same rule as IMAP) and they`re not working. I am really opened for suggestions and willing to experiment, because postponing the problem is not really a solution.

Edit: I have also tried adding another SMTP port(2525) if somehow our provider is filtering standart ports. No changes, still getting the same error, that the server could not be reached on sedning.

Edit 2: Got it working!

As a last resort of frustration, i started experimenting with all settings both on Kerio Connect and Kerio Control. Seems that the problem lies beneath ports 8000(range 0-8000) of Kerio Control.

The fix:

Runnning SMTP service at ports 25, 2525 and 8801.
At port 25, Outlook fails to send mail from external network, can send from internal.
At port 2525, Outlook fails to send mail from external network, can send from internal.
At port 8801, Outlook can send from external and internal netowrks.

All ports are routed by the same rules at all levels(e.g. all ports hit router`s DMZ to Kerio Control, all these ports hit the rule to redirect to mail server, Kerio connect listenning on all ports).

Now, after the problem is solved i don`t care that much what is the problem for properly routing SMTP in port range 0-8000, but I am still curious.

[Updated on: Fri, 04 July 2014 13:57]

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