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Exchange 2016 and Exchange 2019 Certificate Management - Post April 2022

In April 2022 Microsoft released CU 23 for Exchange 2016 and CU 12 for Exchange 2019.
While these updates, which were much delayed, were very welcome, one of the changes which wasn't announced was the removal of the GUI management tools for SSL certificates.
With Exchange being heavily web based since Exchange 2010, SSL certificates play a key part in ensuring Exchange and its clients work correctly. The GUI controls have been in place since Exchange 2010 was released.
However the commands used for Exchange 2007 don't work, so a new set of commands is required.

 

Renewing an Existing Certificate

 

For most people, you will be renewing the certificate. If you don't have any changes to make to the current certificate settings, then a simple on-liner of PowerShell will issue a new renewal request for you to use with your preferred SSL provider to get a new certificate - just enter the thumbprint of the current certificate in the sample below:

 

$txtrequest = Get-ExchangeCertificate -Thumbprint 123456789012344567890 | New-ExchangeCertificate -GenerateRequest

[System.IO.File]::WriteAllBytes('C:\SSL\renewal.req', [System.Text.Encoding]::Unicode.GetBytes($txtrequest))

 

Use get-exchangecertificate on its own to list the certificates currently installed so that you can get the thumbprint.

 

New Certificate Request

 

However if this is a new server installation, or you need to change the current certificate configuration (for example to remove autodiscover.example.com as you are in hybrid), then you will need to create a new certificate request.
Another one-liner will do this, but does need to be constructed beforehand with the relevant information:

 

$txtrequest = New-ExchangeCertificate -GenerateRequest -SubjectName "c=GB,o=Test Company,cn=mail.example.com.com" -DomainName autodiscover.example.com,mail.example.net,autodiscover.example.net

[System.IO.File]::WriteAllBytes('\\Exchange01\ssl\example.req', [System.Text.Encoding]::Unicode.GetBytes($txtrequest))

 

Picking apart that request…

The first part is the ISO two letter designation for your country, followed by your company name.
cn= is the common name, which is usually the name used for OWA/ActiveSync etc as it will appear directly on the SSL certificate. In the old wizard, it would be set to the root of the domain (example.com) but most people would change it to mail.example.com or whatever URL they were using for OWA.
The -DomainName elements are the additional names on the certificate. If you are supporting multiple domains with Exchange and need Autodiscover to work directly, rather than one of the other methods, you need to include them here.
Finally is the location to place the certificate request. Unlike the first one-liner, this requires a file share, just like it did with the wizard. As with the old wizard, I would create a dedicated share for this process on the Exchange server, and give everyone full control. That will ensure that Exchange can write to it.

 

Completing the Certificate Request

 

Whether a new or a renewal request, once you have the certificate issued by the SSL provider, you need to get it in to Exchange.

Use the same share as above…

 

Import-ExchangeCertificate -Server Exchange01 -FileData ([System.IO.File]::ReadAllBytes('\\Exchange01\ssl\response.cer'))

 

Where -server Exchange01 is the server where the certificate request was generated.

 

Exporting the Certificate for use on Other Servers

 

If you have multiple servers you will need to export the certificate to a PFX file, and then import back in again.

 

Once again, run get-exchangecertificate to find the thumbprint, then put it in the below one-liner. You will probably want to use a more secure password as well! Note that this command exports to a local folder, not a file share.

 

$bincert = Export-ExchangeCertificate -BinaryEncoded -Thumbprint 98765432109876543210 -BinaryEncoded -Password (ConvertTo-SecureString -String 'Password123' -AsPlainText -Force)

[System.IO.File]::WriteAllBytes('C:\SSL\export.pfx', $bincert.FileData)

 

To import the file, use the following command, which goes back to using a file share for the source

 

Import-ExchangeCertificate -Server Exchange02 -FileData ([System.IO.File]::ReadAllBytes('\\Exchange01\ssl\export.pfx')) -Password (ConvertTo-SecureString -String 'Password123' -AsPlainText -Force)


Enabling the Certificate

 

With the certificate now installed, the final step is to enable it.

 

enable-exchangecertificate -ThumbPrint 98765432109876543210  -Services IIS

 

Services can be IIS, SMTP, IMAP and POP - any combination of them.
If you choose to include SMTP and get a prompt to replace the default certificate, then choose no. 

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