Following up the post about migrating public folders to the modern version introduced in Exchange 2013, an entry in a TechNet forum asked whether Outlook Web App (OWA) supported shared calendars held in public folders. This came as a kind of throwback to me as it’s a long time since I put anything other than a message in a public folder.  However, public folders have long supported the ability to store calendars, contacts, and tasks so that these data can be accessed by groups of user. Outlook detects the type of information stored in the folder and displays the appropriate user interface, such as a grid to show a calendar.

Specifying what a new public folder will contain

You define the kind of information held in a public folder when it is created with Outlook. I can’t remember if this was ever possible with any version OWA; it certainly is not with OWA 2013 running against either the on-premises or cloud version of Exchange 2013. Once set, there doesn’t seem to be a good way to change the type of information held in a public folder. Certainly there is no parameter in the Set-PublicFolder cmdlet to do the job. Equally, there is no way to set the type of information for a new folder when the New-PublicFolder cmdlet is run as this will create a public folder capable of storing messages.

Microsoft upgraded OWA in Exchange 2013 CU1 to allow it to display public folders. However, two major restrictions exist. First, OWA can only display modern public folders. In other words, you have to complete your migration to Exchange 2013 and then execute a public folder migration before OWA can be used. No access is possible to legacy public folders. Second, OWA can only display “mail public folders”, or public folders that contain “mail and post items” (as they are referred to by Outlook). Other folders (calendars, contacts, tasks, notes, InfoPath, and journal items) are unsupported.

Note that “mail public folders” are different to “mail-enabled public folders.” The former are public folders that hold mail and post items while the latter are public folders whose properties have been updated (for instance, by adding an SMTP address), so that they can receive email (you can also send messages on behalf of a mail-enabled public folder). You can mail-enable a public folder using the Enable-MailPublicFolder cmdlet or through the Exchange Administration Center (EAC).

The problem that we face is therefore to know whether any non-mail public folders exist in a hierarchy so that we know if users need to be told that they have to use Outlook to access these folders. It’s better to know this kind of stuff up front rather than have users swamp the help desk demanding to know how to get to their favourite shared calendar or contact list with OWA.

This command will return any public folder that stores anything other than plain old mail and post items. You can run it against legacy public folders on an Exchange 2007 or Exchange 2010 server or against a migrated set of folders on Exchange 2013. It even runs against public folders created on Exchange Online (Office 365).

Get-PublicFolder –Identity “\” –Recurse –ResultSize Unlimited | Where-Object {$_.FolderClass –ne “IPF.Note”} | Format-Table Name, FolderClass

Scanning for public folders

I give no guarantees as to how quickly this command will run against a large public folder hierarchy. All I can say is that it will be quicker than you can find them manually.

Microsoft might update OWA in a future release of Exchange 2013 to support the display of public folders containing calendars, tasks, and so on. We live in hope!

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