Some Exchange Server 2007 and Exchange Server 2010 roles require Internet Information Services (IIS) to function.   On these servers Exchange will install a series of IIS virtual directories.  In this post I will describe the Exchange Server virtual directories and their purpose.

/owa – This is the directory for OWA (Outlook Web Access on Exchange 2007, and now called Outlook Web App on Exchange 2010), which is the web browser version of Outlook that is usually accessed by remote workers.  The /owa directory is for access to Exchange 2007 or 2010 mailboxes.

/Public – This is the directory used by OWA users when accessing any Public Folders in the organization.

/Exchweb – This directory is used for OWA access for Exchange 2003 or 2000 users but is not usually accessed directly by the end user.  The OWA session will automatically refer the connect to this virtual directory when necessary.

/Exchange – This directory is again used for OWA access.  When an Exchange 2003 or 2000 mailbox user access the /Exchange virtual directory they are proxied to their mailbox.  For Exchange 2007 or 2010 mailbox users they are redirected to the /owa directory for their mailbox access.

This is useful during the transition from legacy Exchange versions to 2007 or 2010, because users can continue to connect to the /Exchange directory and the result will always be that they connect to their mailbox, as long as the server does not run the Mailbox Server role.  In other words, the /Exchange directory only works for legacy mailbox users if the server is a dedicated Client Access Server (though it can also contain the Hub Transport Server role without a problem)./Exadmin – this directory is for administrative purposes only.  Normal users cannot access this directory.

/Microsoft-Server-ActiveSync – this directory is for ActiveSync clients to connect to mailboxes.  These are typically mobile phones or smart phones that have an ActiveSync-compatible email application.

/OAB – this directory publishes the Offline Address Book for clients running Outlook 2007 and above.  Earlier versions of Outlook download the OAB from Public Folders instead.

/Autodiscover – this directory publishes Autodiscover information.  Clients running Outlook 2007 and above, and some ActiveSync clients, can query Autodiscover for a user’s mailbox configuration and automatically set up the mail profile without the end user needing to enter details such as server names.

/EWS – this directory publishes Exchange Web Services, a new programming API that makes Exchange data available to third party applications.

/Rpc and /RpcWithCert – these directories are for Outlook Anywhere, which was formerly known as RPC-over-HTTPS.  As the name suggests, this allowed Outlook clients to make an RPC connection to the Exchange server over an SSL encrypted tunnel from anywhere, making it possible for staff on the road to continue using Outlook without interruption.

/UnifiedMessaging – this directory allows access to Unified Messaging Web Services.  Unified Messaging is Exchange Server’s telephony integration, with features such as voicemail, auto attendants, and Outlook Voice Access.  This virtual directory allows the integration of Outlook and OWA with Unified Messaging for features such as voice mailbox PIN resets and playing voicemail messages within OWA.

/PowerShell – this directory, appearing only in Exchange 2010, allows remote management sessions from the Exchange Management Shell.

/ecp – this directory, again new to Exchange 2010, publishes a self-service control panel for administrators and users.  A broad range of administrative tasks can be delegated to power users and made accessible through the Exchange Control Panel, such as creating new distribution groups and managing SMTP addresses for mailbox users.  Normal users can also access self-service options such as updating their personal information.