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Exchange 2010 Archiving Considerations

Published on August 3, 2009 by in email

Email servers were never designed to archive email messages for long periods of time, apply organizational retention and disposition policies, or perform fast search across an entire email environment. However, the email landscape has changed considerably and organizations that must contend with these requirements have increasingly turned to archiving solutions to fill this need. With Exchange 2010 (E14), Microsoft will be introducing first generation email archiving and there have been many questions on what this will mean for third-party archives, many of which are provided by Microsoft Gold Certified Partners.

As with many software solutions, it usually takes a few versions to work out the kinks and also add the basic feaure requirements and Exchange 2010 is no different. Indeed, Microsoft employees discussing Exchange 2010 features have suggested some requirements may still be better addressed by third-party archives and even the continued use of PST files. The following are some key considerations when looking at Exchange 2010 archiving and other third-party solutions:


  1. Limited Enterprise-Wide Search
    • Description: In Exchange 2010, eDiscovery searches are limited by Exchange organization and multi-Org searches cannot be performed. Users that require offline access also will not be covered as Exchange 2010 archiving will not support offline access (see more below) and PST files have been suggested as a continued solution for these uesrs. Finally, you will not be able to search across other repositories including Windows file shares, SharePoint, and other non-Microsoft repositories.
    • Impact: Exchange 2010 is providing more eDiscovery search capabilities; however, the capabilities still appear to fall short of the ultimate requirements and may require the Exchange data be exported to another eDiscovery solution for more comprehensive search and litigation hold. As eDiscovery needs to cover all ESI within the organization, third-party archives are still ahead in performing full enterprise-wide search of unstructured content by query terms, custodian, and more advanced features such as faceted search and clustering.
  2. No Legal Holds for Public Folders
    • Description: Exchange 2010 supports legal holds for user mailboxes but not for public folders.
    • Impact: All responsive ESI must be preserved when litigation is anticipated. A data map that shows ESI stored in Exchange public folders naturally leads to the question of how that information is collected, preserved, reviewed, and produced. Because Exchange 2010 will not handle public folders, organizations using this feature may wish to consider or stay with a third-party solution.

Costs and Manageability

  1. Increased Primary Exchange Mailbox Database Sizes
    • Description: One of the primary goals of many Exchange administrators for years has been to reduce the sizes of active Exchange stores, primarily by limiting mailbox sizes and having user’s store archived email in PST files. While moving email off of Exchange to PST files was considered best practices at one time, this is no longer the case as organizations seek to better manage their email. Exchange 2010 will reverse this process by moving all of a user’s email back to the Exchange server, on to the user’s primary mailbox database.
    • Impact: By moving additional email messages on to the Exchange primary mailbox databases, organizations will have to contend with increased storage costs as well as longer backup and retore times. Organizations that wish to keep their older emails off of Exchange for infrastructure management will want to continue to look to third-party archives.
  2. Increased Exchange Storage Requirements (Elimination of SIS)
    • Description: Single-Instance Storage, a leading de-duplication technique that has existed in Exchange since 4.0, has been removed. A key reason for this is that Exchange’s design of increasing the number of stores and databases reduces, if not entirely eliminates, the storage benefits afforded by SIS. This occurs because duplicate messages are not distributed within individual Exchange databases. SIS has been replaced by in-store compression which according to some Microsoft MVPs will only cover easily compressible email parts such as headers and message bodies. Email attachments, which are often already compressed (e.g. Microsoft Office 2007 files) will see little benefit and are reportedly not covered.
    • Impact: Replacing SIS with a solution that covers email headers and bodies will not be effective in controlling storage. According to Radicati Group, attachments account of 85% of all email data. As more and more attachments come in a pre-compressed state (Office 2007, PDF, ZIP, JPEG, etc. files), it may be unlikely in-store compression can offer storage savings compared to a global SIS solution. Some SIS solutions from email archive vendors can SIS all of an organization’s email, without having the per-database limitations imposed by Exchange.
  3. Requirement to Upgrade to Outlook 2010
    • Description: Outlook 2010 will be required to access Exchange 2010 Archives.
    • Impact: Organizations will need to upgrade to Outlook 2010 to have manage email using Exchange 2010 archiving; however, this will not support offline access (see below). Many third-party archives will continue to support multiple versions of Outlook in a managed email environment.
  4. No Offline Access to the Archive
    • Description: Road warriors often need access to email offline or in an otherwise disconnected mode. PST files provided a way to achieve this because the email could always be located with the user, whether it was on a plane, train, or in an automobile. With Exchange 2010, there will be no offline access and Outlook users will need to have live access to Exchange 2010′s archive mailboxes. At this time, there are no plans to add this capability.
    • Impact: Some high value users may not find it acceptable to require a live connection to Exchange to access their email. An offline capability will need to exist eventually before these users will be willing to move their email into an Exchange 2010 archive.


Email management has become a pressing need for organizations that need to manage that data for retention, disposition, and E-Discovery. Exchange 2010 is a step in the right direction, but as with many first generation products, it has large functionality gaps before it can replace the archive solutions that are in place and fulfilling requirements today. For now, analyze your requirements and decide if Exchange 2010 will meet your requirements or if it still makes more sense to use a purpose-designed archiving system.

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2 Comments  comments 
  • Martin

    Nice article John. Its Microsoft MVPs and not MPVs btw.

  • John Wang

    Thanks for catching the typo Martin. It’s fixed now.