Having recently found the time to watch the Microsoft Exchange 2019 Ignite session, I wanted to share my thoughts on the next version of Exchange:

Targeted Audience

Exchange Server 2019 is being targeted at large on-premises customers. A lot of the new features and recommendations around Exchange 2019 are around making Exchange secure and increasing performance. Microsoft have said that they believe the best option for hosting mailboxes is in Exchange Online, and this is where the user experience is best. New features and functionality will be rolled out to Exchange Online, and some of those features will not be seen in Exchange on-premises. However, they also understand that some businesses simply cannot move to Exchange Online and therefore Exchange 2019 focuses on providing a secure and better performance.

Unified Messaging

UM is no longer available from Exchange 2019. This will make the planning and deployment of Exchange less complex, however, it also provides a headache for those wishing to migrate to Exchange 2019 that do currently use UM. Microsoft have mentioned the options available to customers:

  • Move to Office 365 – Office 365 can provide UM capabilities with Exchange Online.
  • Migrate to Skype for Business Server 2019 – If your UM is integrated with Skype for Business, you can migrate to Skype for Business Server 2019 and use Cloud Voicemail. This does require your users to be synchronised to Azure AD.
  • Remain on Exchange 2016 – Support for Exchange 2016 runs until 2026. If there are no other requirements to move to Exchange 2019, there is plenty of time to run Exchange 2016 until support runs out.
  • Use 3rd Party solution – Obviously Microsoft’s least preferred option, but a 3rd Party solution can provide UM features using EWS or SMTP.

From my point of view, you can see Microsoft urging for the use of cloud-based services for UM. However, if you are staying on-premises the likely hood is you do not want to use cloud-based features and so may end up moving to aa 3rd Party solution. Time will tell.


Search within Microsoft Exchange has been rearchitected. This is now based on Bing technology and no longer uses Search Index Files. Instead the indexes for search are now built inside each mailbox in the database. Thus removing the annoying Content Index Search failures that can sometimes plague an Exchange environment.

Storage Considerations and the MetaCache Database (MCDB)

Microsoft believe they have reached the limits of cheap storage. Disks are getting bigger, which is great, but the performance within Exchange is not. Exchange has now been designed to use tiered storage. For instance SSDs and JBOD. The MetaCache Database (MCDB) has been designed for use with tiered storage and stores items that are to be quickly accessed on the SSD disks. Items such as Index Data (for search), Mailbox Folder Structure and even small email messages. The intention for this is to provide the following benefits:

  • Faster Search
  • Faster Logon
  • Provide better performance for VDI online clients
  • Faster retrieval of small email messages

The data stored in the MCDB is handled by Exchange, you do not have any control over this. HA has also been built in to the MCDB. If the SSDs were to fail then the MCDB will be available via the disks in JBOD.

It’s an interesting concept and one I would like to see in production to experience the performance benefits. But I think this would only really benefit the larger organisations. However, as mentioned, this is who Microsoft are targeting for this version of Exchange.

Dynamic Database Cache

Dynamic Database Cache was announced as a new feature in Exchange 2019. In Exchange 2016, memory would be allocated per mailbox database evenly, whether that mailbox database was active or passive. With Dynamic Database Cache, more memory is allocated to the active copy than the passive copy. This will mean that more transactions happen in the memory, with less going to the disk, hence better performance.

Exchange 2016 will split the memory allocation across all databases, regardless if they are live.

Exchange 2019 will give more memory to the active database than it will the passive database copies.

Exchange 2019 will also dynamically shuffle the memory allocation should more databases become active on the server.

This is a nice additional feature within Exchange 2019 and I believe will help increase performance in deployments.

Client Access Rules

Client Access Rules have been introduced in to Exchange Online and allow an organisation to prevent access to mailboxes based on conditions such as IP Address, Protocol and User properties. This capability is now being introduced in to Exchange 2019, however, only for the PowerShell and ECP virtual directories to begin with. Additional rules are intended to be added in future CUs. This can work in a coexistence deployment too, but all clients must be pointing to Exchange 2019.

This will help lock down access to Exchange if presented externally. By specifying a required IP address range to access ECP and PowerShell, access to these endpoints would restrict access to the administrative areas of Exchange whilst still allowing access to mailboxes via MAPI over HTTP, OWA, ActiveSync and EWS.

Modern Authentication

Modern Authentication is coming to Exchange on-premises! This is an item that was on the roadmap, so will not be available for release. However, this will help secure authentication requests to Exchange 2019 instead of using legacy authentication methods, like basic auth. Hybrid Modern Authentication is available for Exchange on-premises, but this sends authorisation requests to Azure AD. I am assuming Modern Authentication with Exchange 2019 with authorise in Active Directory, but not much more information was provided. Watch this space!

Another item on the roadmap was the ability to block legacy authentication methods. Blocking Basic Authentication has recently been released for Exchange Online so I would expect o see similar in Exchange 2019. By providing Modern Authentication and blocking legacy authentication, Exchange on-premises will become much more secure.

Outlook Anywhere

One last thing I consider noteworthy is that Exchange 2019 will be removing support for Outlook Anywhere…not at launch, but I believe in a future CU. This is important if looking to upgrade to Exchange 2019 if you are still using Outlook Anywhere (RPC/HTTP). If you are, why? maybe it’s time to look at MAPI/HTTP?



The new features coming to Exchange 2019 are extremely focused on security and performance. It’s clear Microsoft want customers to be using Exchange Online, this is where the user experience will be best, especially in terms of collaboration with the other services within Office 365. However, for those that need to remain on-premises, Exchange 2019 would be a solid option to upgrade to. Even from Exchange 2016, the additional security and performance would be worth the time spent upgrading in my opinion.

I look forward to getting my hands on Exchange 2019 in a live environment to see how it handles and how it compares to Exchange 2013/2016.