Outlook Web App: A Few Limitations

Remember that Outlook Web App is browser based, therefore it cannot provide offline access to mailboxes and there are no .PST files.

If the Exchange server hosting OWA becomes unavailable, users are not able to read or send messages. If offline access to files is required, you must select a different remote-access method to Exchange Server.  Outlook 2010 using Outlook Anywhere, POP3, and IMAP clients can cache messages to provide offline access.

Other limitations of OWA that you may anticipate are no Personal Address Book , so you cannot store it locally.  There is also no integration with Microsoft Office, and forget about using Outlook forms.

Exchange Server 2010 Side

• Client Access Server  (RPC to Exchange 2010 Mailbox, HTTP Exchange 2003)
• Exchange Management Console
• Mailbox Server
• Active Directory Server
• Authentication Methods:
• Active Directory
  Basic Authentication
  Forms-based authentication
  Role of cookies
• Optional ISA 2006 with Pre-authentication and Web Publishing Load Balancing (WPLB)
•  Unified Messaging

What Happens When You Install the CAS role.  (Client Access Server)

To recap, Exchange Server 2010, as with its predecessors, needs IIS, when you add the CAS role.  The purpose of IIS is to that Exchange 2010 can create and access these four special virtual directories, and thus support OWA clients.  The best server for the Mailbox Role would be Exchange 2010, for instance, they can utilize Windows SharePoint Services.  However CAS will happily connect to the older Exchange 2003 and 2000 back-end servers; but alas, these OWA clients cannot even view SharePoint folders or libraries.

/owa. This is the virtual directory accessed by users whose mailboxes are located on Exchange Server 2010 Mailbox servers.

/Exchange. This virtual directory is only used if you have mailboxes located on Exchange Server 2003 or 2000 back-end servers.

/Exchweb. This virtual directory is required to access mailboxes that are located on Exchange Server 2003 or 2000 back-end servers.  However, by default, requests to the Exchweb virtual directory are redirected to the user’s Mailbox server.

/Public. This virtual directory is particularly used by Exchange 2003 or 2000 OWA clients to access public folders on Exchange Server 2003. 

In a new twist with SP1, Exchange Server 2010 SP1 provides access to public folders on an Exchange Server 2010 mailbox server through this /Public virtual directory.

Troubleshooting OWA

Start with the Exchange Server Best Practices Analyzer.

OWA usage reports from IIS logs through the LogParser too.

The Light Version of Microsoft Exchange OWA 2010

All the glossy reviews, including the above information, feature Outlook Premium; however, there is a cut-down version called Outlook Web App Light (formerly OWA Basic in Exchange 2003.)

Since the regular OWA supports more browsers there are fewer uses for the Light version.

OWA Light has none of these features:

No:- Html messages (plain text only), Spell checker, Search mail (Yes, you can search contacts), Tasks, Categories.  What hit me hardest was the lack of tree control which I am used to in Outlook 2010 and OWA Premium.