Upgrading first CAS server to Update Rollup in mixed environment

Users trying access OWA in the mixed environment and getting "The mailbox you're trying to access isn't currently available. If the problem continues, contact your helpdesk."

In mixed Exchange environment (ie. OWA client access for Exchange 2007 users goes  Exchange 2010 CAS Servers -> Exchange 2007 CAS Servers -> Exchange 2007 User), Exchange 2010 server must have previous version of OWA in it’s OWA folder.

Upgrade Exchange 2007 CAS server to Update Rollup creates new folder of files (like UR12 for Exchange 2007 SP3 created the folder ‘8.3.342.1’) which did not exist on Exchange 2010 CAS servers.

That causes problems for Exchange 2007 users to login.

To fix – copy the folder to Exchange 2010 CAS Server OWA folder (from upgraded Exchange 2007 CAS Server OWA folder) and do iisreset on Exchange 2010 CAS server.

More here: http://exchangeserverpro.com/owa-error-mailbox-trying-access-not-currently-available/ (scroll down to the end).

Journaling Rule for Exchange 2007 requires internal SMTP address

Creating Journaling Rule on Hub Transport that forwards emails to the external SMTP address (by creating Mail enabled Contact and configure Journaling Rule to send emails to that Contact) fails. To fix add internal SMTP address to Contact.

Exchange 2007 and ActiveSync. Which device?

To find out which device user utilizes to connect to Exchange 2007 following powershell command can be used:
Get-ActiveSyncDeviceStatistics -Mailbox domain\blye |
ft DeviceType, DeviceUserAgent, LastSuccessSync

Taken from here: http://www.simple-talk.com/sysadmin/exchange/identifying-exchange-activesync-users-with-powershell/ (with the small change you do have to use "domain\" in front of account name)