I am working on migrating users from Exchange 2007, to 2013 and have found that users with mailboxes in the new environment, are unable to view free/busy information of users with mailboxes in the old environment. 

When I try, Outlook says, "No free/busy information could be retrieved" and "The recipient's server could not be contacted." Both environments are in the same AD domain. I verified that the 2007 users can still see free/busy info for 2013 users.

I found this TechNet article, and had a look at my 2007 web.config file. The directions say to find the "appSettings" section, but I only have an "<appSettings />". I was confused by the escape slash, so I tried the config file two ways.

One:

<appSettings>
<add key="maximumQueryIntervalDays" value="62" />
<appSettings />

Two:

<appSettings />
<add key="maximumQueryIntervalDays" value="62" />

Of course, I restarted IIS Admin after both changes, but they didn't help. Any other ideas?

Thanks.

I haven't had to do that particular fix.

The availability service, which is part of Exchange Web Services, must be working properly for Exchange 2013 mailboxes to be able to see free-busy data.

The first advice I have for you is to consult the event logs on both systems and look for Availability Service events because there may be clues therein.

Hi,

Please replace the value as you mentioned with below command in the wab.config in all CAS server for testing:

<appSettings>
    <add key="maximumQueryIntervalDays" value="62" />
</appSettings>

Note: Before you make any changes to the web.config file, make a copy of the file and store it in a safe location.

Then restart IIS to take effect.

Allen,

How is your suggestion different from what I already tried? They look the same to me.

Thanks.

Hi,

It's different, please look the command carefully.

Also, please pay attention to "Issue #3 - Queries for Exchange 2007 users cross-org fail" section, in below blog about Cross Org Availability using Federation Trust and Organization Relationship, for your reference: http://blogs.technet.com/b/exchange/archive/2011/06/28/cross-org-availability-using-federation-trust-and-organization-relationship.aspx

Okay, I replaced <appSettings /> with:

<appSettings>
    <add key="maximumQueryIntervalDays" value="62" />
</appSettings>

I ran "iisreset" and restarted the IIS Admin service. Outlook still tells me that the recipient's server could not be contacted.

Other ideas?

Have you set the InternalURL and ExternalURL options on the exchange web services virtual directories on the Exchange 2007 CAS servers? To do this, use the below:

Get-WebServicesVirtualDirectory -Server e2k7server | Set-WebServicesVirtualDirectory -InternalURL https://url.domain.local/ews/exchange.asmx -ExternalURL https://url.domain.local/ews/exchange.asmx

More information here: https://technet.microsoft.com/en-us/library/bb676480(v=exchg.80).aspx

Also check that the proxy is not causing problems. You may need to ensure that this URL bypasses the proxy.

Thanks.

The internal and external URLs on the EWS virtual directory point to legacy.hostedDomain.com. Interestingly, I noticed something called the InternalNLBBypassURL. That is set to webmail.hostedDomain.com (that's the domain that Exchange 2013 users point to). Anyone know what that URL is for?

Thanks.

Hi,

For coexist environment with Exchange 2010 and Exchange 2013, all CAS namespace should be point to Exchange 2013, it is what we have in the exchange 2013 deployment assistant.

InternalNLBBypassURL is used for maintain affinity when proxy EWS between Active Directory sites, it is configured with the FQDN of the target server and uses Windows authentication by default. However, we shouldn't change the value of the InternalNLBBypassURL property on a Client Access server. If you change it, you'll break proxy for Exchange Web Services requests.

Okay, I will leave it alone. 

Any other ideas why we can't see free/busy information of Exchange 2007 mailboxes, from Exchange 2013 mailboxes?

Thanks.

If the user is using OWA does Free/Buisy work? also are your clients using Cached Exchange Mode for Outlook? also for Exchange mailboxes in 2007 what version are they using for Outlook. If they are using Outlook 2003 then Free/Busy is distributed via Public Folders.

Will.