Last year, Exchange fellows Andrew Higginbotham, Paul Cunningham as well as the Exchange Team reported on checking, and when necessary configuring, your Offline Address Book (OAB) in your current Exchange Server 2010 environment, prior to installing Exchange Server 2013. Not doing so could result in a complete download of the Offline Address Book created by Exchange Server 2013, titled ‘Default Offline Address List (Ex2013)’.

Today I received a report that there is a different symptom of configuration absence. In this case, the customer reported on the inability to download the offline address book, and upon further inspection the Autodiscover server did not report back on the offline address book URL to use. In other words, OAB information was absent from the Autodiscover response, and Outlook gets confused. Note that this issue was reported in Outlook 2010 after installing Exchange Server 2013 Cumulative Update 10. I’m not sure if this change in behavior was introduced in these later builds of Exchange 2013 or Outlook, but it’s still a good thing to know.

The remedy here of course is to configure any (Exchange 2010) mailbox database with unconfigured Offline Address Book setting, and point them to the default offline address book using:

Get-MailboxDatabase | Where-Object {$_.OfflineAddressBook -eq $Null} | Set-MailboxDatabase -OfflineAddressBook (Get-OfflineAddressBook | Where-Object {$_.IsDefault -eq $True})