Exchange Server in Azure – Part III

In two previous post I blogged about a site-to-site VPN connection to Azure and about installing a Domain Controller (and Azure AD Connect) in Azure. In this blog I will discuss that last server, the Exchange 2019 server in Azure.

The last in most interesting part (in my opinion) is installing an Exchange 2019 server in Azure. This can be your last Exchange server for management purposes, or maybe an Exchange server still hosting (some) mailboxes or performing SMTP Relay. It can be quite expensive to host mailboxes on an Exchange server in Azure, moving Mailboxes to Exchange Online is much cheaper. But then…. If you are already decommissioning your own datacenter… All business requirements are different of course 🙂

Exchange in Azure Setup

Currently Exchange server are located on-premises in a hybrid scenario. There’s already a Domain Controller in Azure, and the Azure AD Connect is running in Azure too. Now I want to install an Exchange 2019 server in Azure and run the Hybrid Configuration Wizard to create a hybrid configuration with the Exchange 2019 server in Azure. Webmail and Autodiscover will point to the Exchange server in Azure as well. In short, the configuration will look something like this:

Inbound mail will be sent to Exchange Online Protection and delivered to mailboxes in Exchange Online. When a mailbox is located on-premises, it will be routed to the Exchange server in Azure and when needed, routed to the Exchange server on-premises.

But first we have to think about sizing the Exchange server in Azure.

Sizing Exchange in Azure

The first question about Exchange server in Azure is sizing the Exchange server. First of all, deploying Exchange on Microsoft Azure virtual machines is supported if all storage volumes used for Exchange databases and database transaction logs (including transport databases) are configured for Azure Premium Storage (please see the Exchange Server Virtualization article on Microsoft Learn.

When you are planning to host active mailboxes on the Exchange server running in Azure then you should use the Exchange 2019 storage requirements calculator to figure out the correct size for the Exchange server. You can find the storage calculator on the Exchange 2019 ISO images in the \Support directory.

If you are planning to install an Exchange server in Azure just for management purposes, or for lab purposes, I would recommend using a ‘Standard d8s v3’ VM. This is a VM with 8 vCPU, 32 GB memory and a maximum of 16 additional disks.
When you create a new VM in the Azure Portal and select ‘see all sizes’ it will show a list of most used virtual machines by Azure users as shown below:

For my own lab environment I selected the DS3_V2 VM. Not the fastest VM, but for my own test- and management purposes it is sufficient, but your mileage may vary of course. Attached to my VM are two SSD disks of each 1TB. Be aware that the disks can be a costly thing, especially in a lab environment! The network interface is connected to the internal VNET that was created earlier, and it is connected to the Microsoft network using a public IP address. I also created a DNS name ( which can be used as a CNAME record for some other DNS name) but that’s not really needed since I can use the public IP address in a regular DNS A record.

Installing and Configuring Exchange in Azure

When you have the VM up and running in Azure and you have configured the storage as required, you can install the Exchange server. This is not different from a regular Exchange server. Install the prerequisite software, patch the machine, install the latest Exchange 2019 Cumulative Update and install the latest security update for this CU.

Configuring the Exchange server in Azure is similar to configuring the Exchange server on-premises. Install a proper certificate, configure the virtual directories (hopefully needless to say, but use a different FQDN in Azure since it is a different site in Active Directory) and configure the transport database on a different disk.

Configure the Network Security Group (NSG) to allow access on port 443 and port 25 from the Internet. Depending on your security requirements, you can configure the NSG of the Exchange server with the IP ranges of Exchange Online ( so only Microsoft can fully access your Exchange server in Azure. If you have clients that need to connect to the Exchange server, they can use a VPN connection (that’s what I typically recommend to customers these days, and what I do in my lab environment).

If you are planning an Exchange server just for management purposes, I would recommend not using a public IP at all and only connect to the Exchange server using the private Vnet. In this scenario there’s no need to publish the Exchange server to the Internet, and all changes to recipients are replicated to Exchange Online using Azure AD Connect. No Internet connection is less prone to external attacks of course. And another interesting thing when using a management server only, you can turn it off when not in use. This can save you quite some money.

The next step is to run the Hybrid Configuration Wizard which you can download from When going through the wizard, select the Exchange server in Azure for the Receive Connector configuration and for the Send Connector configuration.

When finished, add the public IP address of your Exchange server in Azure to your SPF record for outbound mail, or configure the SMTP connector to Exchange Online to route all outbound mail via Exchange Online, that’s up to your requirements of course.

What happened in my scenario, my public IP address was assigned by Microsoft and you never know what happened previously with this IP address, but I had to delist it from SpamHaus before I was able to send out email from my Exchange server.

Then move your resources from the on-premises Exchange server to the Exchange server in Azure and decommission your Exchange server on-premises when needed.


In the past three blogpost I explained what it takes to install an Exchange server in Microsoft Azure and it contains of the following steps:

  • Create a site-to-site connection between your on-premises network and a Vnet in Azure.
  • Install a Domain Controller in Azure, connected to the Vnet. Optionally you can install an Azure AD Connect server in Azure as well.
  • Install and configure an Exchange server in Azure, connected to the Vnet (and to the Internet when needed)

An Exchange server in Azure is fully supported, as long as the Mailbox database and transaction logfiles are located on premium storage, that should be no problem.

Sizing your Exchange server in Azure is like an on-premises Exchange server. Use the storage calculator to determine the size of your Exchange server, and look for a VM that matches these requirements.

When installing an Exchange server in Azure just for management purposes it’s much easier. You can use a relatively lightweight Exchange server, there’s no need to publish it to the Internet (much safer) and you can turn it off when not in use.

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