Back to Blog

Running Exchange 2010? Start Planning Your Exchange 2016 Migration Now

Image of Steve Goodman
Steve Goodman
Exchange migration flowchart

Exchange Server 2016 has arrived and has been lauded as one of the most reliable releases of Exchange yet. In many ways, it’s an evolution of the core technologies built into Exchange Server 2010 – but the way it’s put together has been revolutionized, making deployment choices much more straightforward.

What’s new compared to Exchange 2010?

Exchange Server 2010 has been extremely popular and, for many, was the upgrade point from Exchange 2003. It revolutionized availability with Database Availability Groups and made it possible and practical to deploy site resilient Exchange with relative ease. Six years have passed since its original release, though, and in that time, Microsoft has learned a lot from running the world’s largest Exchange deployment inside Office 365.

Much is new under the hood, including a rearchitected Store engine and better automated availability checks, but some of the most interesting deployments include:

  • A beautiful new Outlook Web App – renamed “Outlook on the web” providing near parity with the Outlook client, offline access and fantastic cross platform support, even on mobile devices.
  • A new management GUI, known as the Exchange Admin Center, replaces the Exchange Management Console. This makes common tasks easier, and the second iteration has been improved based on nearly three years of feedback.

  • A move to a single-role server architecture, combining all client access, mailbox, transport and unified messaging into every installation.

  • Simple namespace planning with no client affinity required and HTTPS namespaces that can span multiple datacenters.

  • No direct MAPI access to Mailboxes. All access is via HTTPS.

  • Removal of traditional public folders, replaced by Modern Public Folders living inside normal mailbox databases.

  • Better database reliability including shorter database switchover times with transparent failover to users and technology to automatically patch corrupt database pages from other copies.

  • Database auto-reseed, support for very large disks and support for multiple databases per disk.

  • Drastically lower IO requirements compared to Exchange 2010, with potentially less IO required in planned Exchange 2016 updates.

What killer features should I buy Exchange 2016 for?

There’s a lot to like in Exchange 2016. The real value is in the simplified architecture, which promotes easier management and better reliability. Email is core to any organization, and you need it to be reliable. The end-to-end improvements all add together to make this happen – whether it’s using the new MAPI/HTTP protocol for client access, or if it’s ensuring databases are less likely to fail.

If you already have a reliable architecture on Exchange 2010, then there is a lot of money to be saved when you next upgrade. The preferred architecture, introduced in Exchange 2013, provides guidance on how to deploy Exchange in a way that provides maximum reliability at a low cost. Lower IO requirements and the ability to realistically avoid the use of RAID means you can make significant savings on disks required and also remove the requirement for traditional backups.

Client access improvements simplify deployments and mean you can have a single name across the entire organization if you want to. Office 365 does this globally with the “” name, and it’s practical for your own multi-site deployment, too. Load balancer improvement can in some cases negate the need for a load balancer or make it simpler to manager.

From a client perspective, the new Outlook on the web is a revolution compared to Exchange 2010 and makes OWA in Exchange 2013 look quite antiquated. If you have a large number of OWA users at the moment, the new interface will make a day-to-day difference immediately.

Do I lose any functionality when I upgrade?

You will lose compatibility with older clients, like Outlook 2003 and Outlook 2007. If you still have versions of Office this old, then you will need to upgrade clients before moving the mailboxes they use.

If you prefer to deploy separate roles, such as separate Client Access Servers, then you lose the ability to separate these. This is a good thing, though, because the reliability and simplicity of Exchange 2016 deployments relies on all the logic for a particular mailbox running from the same host.

Modern Public folders store Public Folder content inside special mailboxes, which are stored on normal mailbox databases. These are replicated using normal Database Availability Groups rather than traditional multi-master replication in Exchange 2010 and earlier. If you have particular Public Folders that are replicated and used across disperse geographies, then you lose the lower-latency access those in-region users have. They will need to connect back to the single active copy.

Applications that rely on MAPI CDO API access to Exchange no longer function. It’s important to ensure your third-party applications support newer APIs, like Exchange Web Services.

OWA is improved, but some things have been removed, including the add new functionality. The ability to add an additional inbox (for example, from a shared mailbox) into users’ own OWA view has been removed. They’ll have to use the more commonly used “Open additional mailbox” feature. If you use Public Folders extensively in OWA, then you’ll need to add your favorites rather than navigating and accessing them on-demand via a tree-view.

What are the upgrade paths?

If you are running Exchange 2010, you can migrate directly to Exchange 2016. No version of Exchange since Exchange 2000 supports in-place upgrades, so you must implement new servers and storage to migrate to.

If you are running a simple implementation, such as a combined Client Access and Hub Transport, plus a single Mailbox server, then the logical route will be to implement, as a minimum, one Exchange 2016 server:

Picture 1

Larger organizations taking advantage of high availability features should also consolidate as part of the migration but will need to create new database availability groups to migrate mailboxes to. You will implement Exchange 2016 side-by-side with Exchange 2010, then move mailboxes across:

Picture 2

Exchange 2016 allows for a single namespace to be used when migrating to Exchange 2010. If you have upgraded from Exchange 2003 or 2007 to 2010, then not having to implement a legacy namespace will be a pleasant surprise.

As part of the configuration process, you will move your Exchange 2010 HTTPS namespaces, such as “” across to Exchange 2016, along with services like Autodiscover. Exchange 2016 will then proxy back client access to the correct server.

Picture 3

Before I start upgrading what do I need to check out?

As with any major upgrade, you will need to check out a number of key areas. Along with the core requirements stated by Microsoft on TechNet, it’s worth looking at the following areas:

  • Third-Party Software – Do you run any software that relies on Exchange? Signature software, Mobile Device Management software, Anti-Virus Software, Backup Software and much more relies on specific versions of Exchange. It is extremely likely that these will need upgrading before they can be used with Exchange 2016.

  • MAPI Client Access Array and HTTP Namespaces – If you use the same name for the HTTPS name for Exchange and the MAPI Client Access array then you may have an issue when you move to Exchange 2016. The client-facing server names used for services like OWA should be different from the name used internally for Outlook MAPI clients.

  • Internet publishing of services – If you are still using a solution like ISA or TMG to publish Exchange 2010, it is time to look at alternatives. TMG is still under support but does not come with rules and examples for use with Exchange 2016. Load balancing and Internet publishing are simpler in Exchange 2016, so if you do have to replace TMG, you're likely to find that cheaper load balancers are more than capable of meeting demanding requirements.

  • Capacity available – Exchange 2016 requires more CPU and RAM than Exchange 2010, but is less demanding of disk performance. Calculators for Exchange 2016 haven’t been released yet – but you can get an estimate for what you are likely to need by using multi-role examples from the Exchange 2013 sizing calculators.


It’s time to start planning to say goodbye to Exchange Server 2010. It has been reliable – but improvements in subsequent versions are compelling and Exchange 2010 is in extended support, meaning it is edging closer to the end of life. Exchange Server 2016 is proving reliable – and of course used by millions of users daily in the Office 365 service. If you are planning to stay on-premises, start your planning now..

Exchange Coexistence

Exchange 2013 OWA Coexistence with Exchange 2010

Image of ENow Software
ENow Software

Outlook Web App (OWA) has been a mandatory requirement for every organization. When Exchange 2013...

Read more
Microsoft Exchange Security Updates banner image

January 2023 Exchange Security Updates

Image of Jaap Wesselius
Jaap Wesselius

On January 10, 2023, Microsoft released new Security Updates for Exchange 2013 CU23, Exchange 2016...

Read more