When using Outlook 2007 in Cached Exchange Mode users can access their email and can read emails while in an offline mode. But when they try to access additional mailboxes and shared mail folders they note that they are only allowed to do so when the mailboxes and shared mail folder are available only in an online mode. There are some workarounds which will allow them to access additional mailboxes and shared mail folders in the offline mode.
Even though shared mail folders cannot be cached users can cache any other shared folder though such as Contacts, Calendar and Public Folders.

Additionally, if an administrator has granted full mailbox access to those additional mailboxes, then they could be set up as IMAP accounts. An email administrator can help with the IMAP settings.

Support for caching shared folders with Cached Exchange Mode depends on the version of Outlook that is running. There are workarounds for Outlook 2003 and Outlook 2007 but if administrators don’t want to spend time on implementing workarounds then they can upgrade to Outlook 2010 which has full caching support for additional mailboxes.

For administrators who need to continue to use Outlook 2003 and Outlook 2007 here are some of those workarounds.

• IMAP can be used for additional mailboxes.
  IMAP supports caching and syncing of email folders with the server mailbox. In order to connect to an additional mailbox as an IMAP account an administrator will need to grant full mailbox permissions on the additional mailbox. An Administrator can also create the IMAP settings for the mailbox.
• Configure an additional email profile.
  Once full mailbox access has been granted to the additional mailbox then an administrator can also configure it with its own mail profile. This will allow the mailbox to be cached since the mail profile the additional mailbox will be a component of the main mailbox. In order for the new mail profiles to be recognized, and the cache updated, the changes will require a restart of the Outlook client.
• Store shared data in a Public Folder.
  If only one or a small number of folders need to be shared then it might be easier to store the shared data in a Public Folder. This workaround will still allow full control of access to the folder by the owner. It will also allow the folder to be cached for off line usage if the Public Folder has been identified as a Favorite Folder.
• SharePoint is another workaround for sharing content.
  If your company is using SharePoint, then you can also share content via the SharePoint website. The benefit of this workaround is that Outlook can also connect to SharePoint and cache the contents from the SharePoint site. Outlook 2007 and SharePoint 2007 are needed if your organization wished to share more than just Contacts and Events.
• A pst-file can also be used as a workaround.
  Pst files can be used as a storage file through basic copy techniques. Although this is technically not a sharing or caching methodology, it will still allow end users to work off line with the pst file.  And since pst-files are stored locally they will always have access to their content. In order for files to maintain synchronization it will be necessary for end users or administrators to ensure that any change made to the local copy are manually replicated back to the original files once the user is working online.

Additionally, there is a hotfix available in the Outlook 2007 post-Service Pack 1 hotfix package that is dated February 24, 2008. Administrators can find for more information about the hotfix by viewing the following article, 957909 as listed in the Microsoft Knowledge Base.

The hotfix can be enabled by following the steps outlined below:

1. Exit Outlook 2007.
2. Start the Registry Editor. In Windows XP, click Start, click Run, type regedit in the Open box, and then click OK.
3. Locate and select the following registry key:
   HKEY_CURRENT_USERSoftwareMicrosoftOffice12.0OutlookCached Mode
   As an alternate an administrator can also use the following registry key:
   HKEY_CURRENT_USERSoftwarePoliciesMicrosoftOffice12.0OutlookCached Mode
4. Right click CacheOthersMail, and then click Modify.
5. In the Value data box enter a value of “1”. Next, click OK.
6. On the File menu, click Exit to exit Registry Editor.
7. Disable the headers with the following steps:

• On the File menu, click on “Cached Exchange Mode”.
• Clear the following options by selecting them:
  -    Download Headers and then Full Items
  -    Download Headers
  -    On Slow Connections Download Only Headers

If header mode is not disabled then it is possible for headers to get corrupted or stop responding.