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In my earlier blog post, I discussed the compelling reasons to consider an upgrade to Exchange 2016.  If your firm will look to pursue an upgrade to Exchange 2016 in the near future, there are a few key changes and requirements to consider in order to be successful.

Coexistence with legacy Exchange:  As mentioned previously, Microsoft continues to support direct migration from two versions prior, meaning that direct migration to Exchange 2016 is only possible from Exchange 2010 and Exchange 2013.  All Exchange 2007 and earlier servers must be completely removed from an environment (and Exchange 2010 and/or Exchange 2013 appropriately patched to Service Pack 3 Update Rollup 11 and Cumulative Update 10, respectively) before the first Exchange 2016 server can be introduced.

Outlook client support:  Similar to legacy Exchange versions, Outlook clients are only supported for two versions prior as well.  This means that only Outlook 2010, Outlook 2013, and Outlook 2016 are supported for connectivity to Exchange 2016[1].

Active Directory functional level:  Exchange 2016 requires the Active Directory domain and forest functional levels to be at Windows Server 2008 or higher.  While Windows Server 2003 has been unsupported since July 2015, many law firms still have legacy domain controllers in place or have simply not yet upgraded their functional levels.

Windows Server operating system:  At release, Exchange 2016 supports Windows Server 2012 and Windows Server 2012 R2 as the underlying server operating system.  Exchange 2016 will also support Windows Server 2016 shortly after its release (expected in the first half of calendar year 2016), which will make deployment options important to understand relative to desired upgrade project timing.  Depending on project scheduling, license purchasing, and more, many law firms will likely choose to wait until Exchange 2016 can be deployed on Windows Server 2016 to avoid deploying a new messaging platform on an operating system that is two or four years old.

Architecture change, again:  Exchange 2010 had five distinct server roles and, as the product matured, Microsoft began recommending a multi-role server architecture, where the Client Access Server, Hub Transport Server, and Mailbox Server roles (along with Unified Messaging Server role, if in use) were collocated on the same physical or virtual machine server.  Exchange 2013 simplified the Exchange architecture by reducing the server role count to three and the recommendation remained to deploy multi-role servers internally (this time comprising the new Client Access Server and Mailbox Server roles).  Exchange 2016 has only two server roles – Edge Transport Server for perimeter network hygiene and mail flow services, and Mailbox Server for all internal network functionality.  This effectively forces the multi-role server architecture paradigm for all environments.

Application integration:  As was discussed openly with the release of Exchange 2013, Exchange 2016 brings the end of MAPI/CDO support within Exchange.  Applications can integrate with Exchange 2016 via Exchange Web Services or the Representational State Transfer (REST) API.  While this support stance was expected given the announcements made with Exchange 2013, many law firms likely have some applications in use (e.g. older mobile device management platforms) that only support the MAPI/CDO and will therefore need to be upgraded or replaced in order to support Exchange 2016.  If any software is in use that was developed by internal developers or smaller software vendors, those applications may not support Exchange 2016 or require substantive effort such that an Exchange upgrade project could be easily derailed before it starts.  As with any Exchange upgrade project, it is beneficial to develop an integrated application matrix to understand the impact of what exists today and what is possible going forward, so that decisions can be made and remediation/upgrade/replacement efforts can get started as soon as possible.

Is it ready?

Fortunately, Microsoft has already released sizing guidance for Exchange 2016, although it should be considered preliminary until sufficient data points exist to hone the recommendations.  Currently, sizing is expected to be similar to Exchange 2013 in the core areas of storage performance and memory, with a slight increase in processor requirements (mostly due to the architecture changes).  This, combined with flexible coexistence options for Exchange 2013 environments, should allow for more options to design and plan for a migration to Exchange 2016.

Exchange 2016, for the reasons above, represents an interesting or perhaps required upgrade for many law firms.  Considering the release delays for both Windows Server 2016 and Office Online Server, it is likely that most firms will plan to pursue their upgrades in the first half of 2016 at the earliest.  However, despite that timing, if an Exchange 2016 upgrade is scheduled for the upcoming year, it is important to begin design and planning efforts as well as integrated application review as soon as possible, so that infrastructure teams, application teams, and procurement are all ready to execute quickly when the time comes.