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