The Availability service improves information workers' calendaring and meeting scheduling experience by providing secure, consistent, and up-to-date free/busy information. By default, this servic...
Updated Jul 01, 2019
Version 2.0
Blog Post
Hi Binny,
Cross-forest Free/Busy does not work with a shared SMTP addrees for the following reason, see the scenario bellow, unless if you're using PF replication rather than availabiltiy service.
1. Outlook 2007 clients in the source forest (Forest A) connect to the EWS InternalUrl to get free/busy information for users from Forest A.
2. For users in the target forest (Forest B), which is a cross-forest request, the CAS from the source forest needs to find A record for autodiscover.forestb.com or make an LDAP call if you exported the SCP from the target forest into the source forest.
3. In the source forest (Forest A), you have all the contacts from the target forest (Forest B).
4. Once you add a contact in outlook 2007, the exchange identifies the contact and knows this is going to be a cross-forest free/busy request.
5. The CAS in the source forest (Forest A) reads the information from Add-AvailabiltiyAddressSpace you ran previously to decide if the CAS is going to query the availability service or a Public Folder
6. In your scenario, you ran the cmdlet to use the Availability service which will depend of the autodiscover.
7. The CAS in the source forest (Forest A) will try to find autodiscover.forestb.com, and then after that will return the EWS InternalUrl of the remote CAS to query free/busy for users in the target forest.
8. Here is the issue, since you have the same SMTP address in both forest. Autodiscover does not work in this type of scenario because it will query the wrong forest that does not have the object, since autodiscover cannot point to different organizations.
10. This is how the code was design to work.
Options to solve the problem:
If you want to keep the same SMTP address on both forest, then you will have to use old fashion way with Public Folder querying the free/busy.
1.Add-AvailabilityAddressSpace -ForestName <example.contoso.com> -AccessMethod PublicFolder
2.Then replicate the Public Folder between both forests.
http://technet.microsoft.com/en-us/library/bb125182.aspx
Cross-forest Free/Busy does not work with a shared SMTP addrees for the following reason, see the scenario bellow, unless if you're using PF replication rather than availabiltiy service.
1. Outlook 2007 clients in the source forest (Forest A) connect to the EWS InternalUrl to get free/busy information for users from Forest A.
2. For users in the target forest (Forest B), which is a cross-forest request, the CAS from the source forest needs to find A record for autodiscover.forestb.com or make an LDAP call if you exported the SCP from the target forest into the source forest.
3. In the source forest (Forest A), you have all the contacts from the target forest (Forest B).
4. Once you add a contact in outlook 2007, the exchange identifies the contact and knows this is going to be a cross-forest free/busy request.
5. The CAS in the source forest (Forest A) reads the information from Add-AvailabiltiyAddressSpace you ran previously to decide if the CAS is going to query the availability service or a Public Folder
6. In your scenario, you ran the cmdlet to use the Availability service which will depend of the autodiscover.
7. The CAS in the source forest (Forest A) will try to find autodiscover.forestb.com, and then after that will return the EWS InternalUrl of the remote CAS to query free/busy for users in the target forest.
8. Here is the issue, since you have the same SMTP address in both forest. Autodiscover does not work in this type of scenario because it will query the wrong forest that does not have the object, since autodiscover cannot point to different organizations.
10. This is how the code was design to work.
Options to solve the problem:
If you want to keep the same SMTP address on both forest, then you will have to use old fashion way with Public Folder querying the free/busy.
1.Add-AvailabilityAddressSpace -ForestName <example.contoso.com> -AccessMethod PublicFolder
2.Then replicate the Public Folder between both forests.
http://technet.microsoft.com/en-us/library/bb125182.aspx