We had configured Availability service across two Exchange 2010 Org without using federation services but following TechNet article https://technet.microsoft.com/en-us/library/bb125182(v=exchg.141).aspx using org-wide configuration using a service account in each forest. This worked flawless without any issue as all auto-discovery information for availability address space was configured correctly and accessible.
Recently one of the Exchange 2010 went in the mixed mode by introduction of Exchange 2013 in a new site while the other remained native Exchange 2010. The cross forest availability configuration continued to work for address space which were already in place without any issue.
However when we tried to introduce new address space using Add-AvailabilityAddressspace -Forestname '2013.Domain' -Accessmethod OrgWideFB -Credential:$a in the native exchange 2010 org , even though the command executed successfully we are not able to access the free/busy information of the users on Exchange 2013 cross forest.
After adding the availability address space we started getting error Event ID 4012 indicating -
Cross-forest proxy request to 2013.Domain could not be initiated due to invalid credentials. Specific error is: The credentials for cross-forest authentication are invalid.
We checked to make sure the Service account is not locked and further validated the service account by access the cross forest autodiscovery url and EWS url using the service account.
Recently we also need to add new domain to availability address space and this domain was add to old exchange 2010 server and we got the same error as above 4012 however old domain added before introduction of Exchange 2013 is still working fine.
When I ran further test
when I ran Test-OutlookWebServices -TargetAddress someone@2010.new.domain and got this error "When querying Availability for the recipient e-mail addresssomeone@2010.new.domainthe following error code and message were received: ErrorProxyRequestProcessingFailed:Unable to send cross-forest request for mailbox <SomeOne>SMTP:Someone@2010.new.domain because of invalid configuration., inner exception: The credentials for cross-forest authentication are invalid."
How do we fix it? Even if the exchange 2013 is not working we should be able to get the address space on exchange 2010 working. Has anything change in 2013 other than giving permission to mailbox server?
Any help is appreciate. This is one of the topic I didn't get much help on the web. Now days the premier support has become pathetic hence don't want to waste hours there. For them this will be either a non supported scenario or third party issue.
With Regards.
M S Ali.
With Regards, M S Ali