Error 4.3.2. from new spam filter on Exchange 2007 - Cant recieve incoming mail

Our old spam filtering company was recently bought out an merged with another company and we have been forced to move all our clients systems onto the new spam filter.

This has been ok with most clients however I have not been able to get it working at all on any SBS 2008/Exchange 2007.

I have added the IP's of the spam filters to the recieve connectors, done everything on the spam filter end to make sure its pointing mail to the right place. Matched the entire setup to an SBS 2011 that is actually working with the new filter and I still get the same result. Mail just piles up in the delivery que of the spam filter and all mail is recieving the error "4.3.2 Service not available, closing transmission channel", you can also do a "telnet test" from the spam filter to your server and you recieve that exact error.

I have tried disabling all firewalls and AV but doesnt effect anything, it is definately the exchange server denying it, because if I stop some exchange services the "telnet test" will just time out instead. Im not sure what is going on here, has anyone ran into something similar or has any idea whats up?

I have double and tripple checked the IP's in the recieve connector are all correct
Have tried rebooting to get the settings to apply
Checked all essential services are running
Disabled AV and Firewalls
Default port 25 is being used and is configured on both ends
Have configured outbound send connector relay through spam filter, and this is working no problem
tom_szaboAsked:
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tom_szaboAuthor Commented:
Ok was able to get this working by creating an additional recieve connector on port 26 and directing mail to that one instead of the default one. Not sure why it works that way and not on the original connector.
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Wayne88Commented:
"you can also do a "telnet test" from the spam filter to your server and you recieve that exact error"

That pretty much what I would focus on.  The traffic from the anti-spam is not reaching the Exchange server so the only thing in between would be router/firewall.  Can you check the firewall logs for indication why the packets were blocked or dropped (if they were)?  If you can be confident that the router/firewall is configured correctly then we can focus on just the server.

Another tool that will help you is the Microsoft Remote Connectivity Analyzer. Run the Internet Email Tests and any other tests that may help then post the results if you will.  Please omit any private information.

https://testconnectivity.microsoft.com
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tom_szaboAuthor Commented:
Can you check the firewall logs for indication why the packets were blocked or dropped (if they were)?  If you can be confident that the router/firewall is configured correctly then we can focus on just the server.

As I said when disabling exchange services I no longer recieve that error and just timeout, so I would say that is a pretty strong indication that the spam filter is reaching the exchange server and no firewall or AV is interfering.

Unfortunately the Microsoft connectivity tests are no good because the MX records just point to the spam filter which is working fine.
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Wayne88Commented:
Ok thanks for getting back, glad you got it solved. Cheers!
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tom_szaboAuthor Commented:
solved
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