Hi,

I hope someone will have seen this before as it is driving me mad, just setting up cross forest free / busy between Exchange 2010 and 2013, lookups work 2013 to 2010 but not 2010 to 2013.

I have double triple checked everything, DNS, Certs, Autodiscover, access to EWS etc and it all looks good but it still doesn't work.  This is the first time I've tried this to Exchange 2013 so I may be missing something but I can't see what..

I found this but is has not helped either! https://support.microsoft.com/en-us/kb/3010570 as I am using DNS and not SCP.

Any help greatly appreciated.

have you run this command

Add-AvailabilityAddressSpace -ForestName targetdomain.com -AccessMethod PerUserFB -UseServiceAccount $true

Also did you check from OWA.

Hi,

Yes I have added (and removed and re-added) the address space and still no luck, OWA also fails.

Thanks

Hi,

I understand free busy can't work on outlook and OWA.

In cross-forest topologies where all connecting clients are running Outlook, the Availability service is the only method of retrieving free/busy information. So I think the issue is related to availability service.

Have you refer to the below blog when configuring the Availability Service in a cross-forest topology?

http://blogs.technet.com/b/exchange/archive/2011/03/04/3412075.aspx

In the target forest, we need to run the following command:

Get-MailboxServer | Add-ADPermission -Accessrights Extendedright -Extendedrights "ms-Exch-

EPI-Token-Serialization" -User "<Remote Forest Domain>\Exchange servers"

https://technet.microsoft.com/en-us/library/bb125182(v=exchg.150).aspx  

Regards,

David