Category Archives: Office365

Exchange HCW8078 – Migration Endpoint could not be created

While migrating a customer from Exchange 2010 to Exchange 2016, I had to create an Exchange Hybrid Deployment, because the customer wants to use Microsoft Teams. Nothing fancy and I’ve did this a couple of times.

Unfortunantely the Hybrid Connection Wizard failed to create the migration endpoint. A quick check of the logs showed this error:

Microsoft.Exchange.MailboxReplicationService.MRSRemotePermanentException: The Mailbox Replication Service could not connect to the remote server because the certificate is invalid. The call to 'https://mail.contoso.com/EWS/mrsproxy.svc' failed. Error details: Could not establish trust relationship for the SSL/TLS secure channel with authority 'mail.contoso.com'. -->The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel. --> The remote certificate is invalid according to the validation procedure

The customer had not plans to move mailboxes to Exchange Online, so we didn’t care about this error. But the Calendar tab in Teams was not visible, and Teams logs stated that Teams was unable to discover the mailbox. A typical sign of a not working EWS connection.

It’s always TLS… or DNS… or NTP

The customer used a certificate from its own PKI, so it was not trusted by Microsoft. In addition, the Exchange was located behind a Sophos XG which was running Webserver Protection (Reverse Proxy). But this was not the main cause for the problems.

The root cause was the certificate from the customers PKI.

And therefore you should make sure to use a proper certificate from a 3rd CA for Exchange Hybrid Deployments. I really please every customer to stop using self-signed certificates, or certificates from their own PKI for external connections.

The customer has switched to a Let’s Encrypt certificate for testing purposes and the problems went away, without running the HCW again. He will now purchase a certificate from a 3rd party CA.

Access to on-premise hosted Public Folders using Exchange Online mailboxes

Public Folders are still a thing. And while companies are moving their stuff into the cloud, Public Folders still need to be accessed by cloud-located mailboxes.

Allowing the access from Exchange Online mailboxes to on-premise hosted Public Folders is well documented by Microsoft, but there are also some fuzz. I had to deal with this during a Office 365 transition project at one of my customers.

The background

The customer is running a single Exchange 2016 server in a Windows Server 2012 R2 forest. AzureAD Sync is running and its syncing on-premise identities to AzureAD. The customer uses Office 365 E5 plans and he wants to move to Exchange Online, aside other O365 services like SharePoint Online, Teams etc.

Something was missing

After setting up the Exchange Hybrid, the customer and I where able to migrate the first mailboxes to Exchange Online.

To our surprise the on-premise Public Folders were not visible from the migrated Exchange Online mailboxes. We had still things to do…

In order to get the access to the Public Folders working, the Public Folder mailbox object needs to be synced to AzureAD. This is not complicated, because all you need to make sure is, that the user object is synced. If you are using an OU filter for the AzureAD sync, make sure that the OU with the Public Folder mailbox user object is included into the sync.

But there is also a second requirement: You also need to sync the Microsoft Exchange System Objects container! This is pretty important and it is not mentioned in the docs (Public folders in Microsoft 365, Office 365, and Exchange Online).

Check if the user is synced by using the Exchange Online PowerShell. This is how the Public Folder mailbox user looks like from the Exchange Online perspective:

PS C:\Users\p.terlisten> Get-MailUser Mailbox1

Name                                     RecipientType
----                                     -------------
Mailbox1                                 MailUser

This is the Public Folder mailbox that is hosted on-premise.

PS C:\Users\p.terlisten> Get-Mailbox -PublicFolder

Name                      Alias                ServerName     ProhibitSendQuota
----                      -----                ----------     -----------------
Mailbox1                  Mailbox1             EX             Unlimited

As long as you can’t see the MailUser in Exchange Online, you have no chance to configure the Public Folder access.

The next step is to synchronize the mail-enabled Public Folder objects to Exchange Online. For this, you have to download two scripts from Microsoft.

  • Sync-ModernMailPublicFolders.ps1
  • Sync-ModernMailPublicFolders.psd1

Run the Sync-ModernMailPublicFolders.ps1 script on your on-premise Exchange server. You will need your Office 365 admin credentials for this task.

PS C:\Users\p.terlisten\Download> .\Sync-ModernMailPublicFolders.ps1 -Credential (Get-Credential) -CsvSummaryFile:sync_summary.csv

The last step is to enable the Public Folder access using the Set-OrganizationConfig cmdlet in the Exchange Online PowerShell session.

PS C:\Users\p.terlisten> Set-OrganizationConfig -PublicFoldersEnabled Remote -RemotePublicFolderMailboxes Mailbox1

Please note that some of these steps need some time to get active! It will take some time for the background tasks to get some things sorted.

Controlled Connections to Public Folders in Outlook

It is worth mentioning that after enabling the access to Public Folders all Exchange online users can see the on-premise hosted Public Folders. If you need to enable the access only for some Exchange Online users, Microsoft has a solution for you: Controlled Connections to Public Folders.

First, you need to enable the Public Folder access for the users you have selected.

Set-CASMailbox "John Doe" -PublicFolderClientAccess $true

Then you enable the feature globally using the Exchange Online PowerShell.

Set-OrganizationConfig -PublicFolderShowClientControl $true

This setting applies only to Exchange Online hosted mailboxes!

Office365/ Exchange OAuth errors after replacing TLS certificate

A customer of mine asked for help to analyse a weird OAuth error. They are using a Microsoft Dynamics 365 Outlook plugin, which came up with an error:

“Can’t connect to Exchange”

In addition to this, they also faced an issueaccessing shared calendars of Exchange Online mailboxes.

Clearly an OAuth error. So we ran the Hybrid Connection Wizard again, which finished without any errors. But the errors persisted. Next stop: OAuth configuration.

We logged into one of the Exchange servers, started an Exchange Management Shell and checked the current OAuth configuration:

[PS] C:\Windows\system32>Get-AuthConfig
RunspaceId : e7c560cd-8316-4d9c-b97d-f4358d665e7d
CurrentCertificateThumbprint : CA420022ACC542D3AF7598456615715E98FFE986
PreviousCertificateThumbprint : E7B56BEAF4704BCBBF8C297F1D8D000215679C6F
NextCertificateThumbprint :
NextCertificateEffectiveDate :
ServiceName : 00000002-0000-0ff1-ce00-000000000000
Realm :
DeploymentId :
IssuerIdentifier :
Name : Auth Configuration
AdminDisplayName :
ExchangeVersion : 0.20 (15.0.0.0)
DistinguishedName : CN=Auth Configuration,CN=EXORG,CN=Microsoft
Exchange,CN=Services,CN=Configuration,DC=domain,DC=tld
Identity : Auth Configuration
Guid : 911b6246-6248-4278-91be-1b7b4943d2f1
ObjectCategory : mlnetwork.local/Configuration/Schema/ms-Exch-Auth-Auth-Config
ObjectClass : {top, container, msExchContainer, msExchAuthAuthConfig}
WhenChanged : 11.04.2020 12:33:12
WhenCreated : 27.02.2015 14:24:37
WhenChangedUTC : 11.04.2020 10:33:12
WhenCreatedUTC : 27.02.2015 13:24:37
OrganizationId :
Id : Auth Configuration
OriginatingServer : DC01.domain.tld
IsValid : True
ObjectState : Unchanged

The CurrentCertificateThumbprint was the thumbprint of the old certificate. So we had to update it.

Set-AuthConfig -NewCertificateThumbprint 45CCEEDFAAB00F3A4312FF56774FA3B3412B9C (get-date)
Set-AuthConfig -PublishCertificate
iisreset /noforce
Set-AuthConfig -ClearPreviousCertificate

After the iisreset, the Dynamics plugin and the Exchange Online calendars started to work again.

Once in a year: How to update TLS certificates on ADFS server and proxies

You might got this news some days ago: Starting with September 1, 2020, browsers and devices from Apple, Google, and Mozilla will show errors for new TLS certificates that have a lifespan greater than 398 days. Due to this move from Apple, Google and Mozilla, you have to deal with the replacement of certificates much more often. And we all know: Replacing certificates can be a real PITA!

Bild von skylarvision auf Pixabay

Replacing TLS certificates used for ADFS and Office 365 can be a challenging task, and this blog post will cover the neccessary steps.

ADFS Server

The first service, for which we will replace the certificate, is the ADFS server, or the ADFS server farm. At this point it is important to understand that we are dealing with two different points to which the certificate is bound:

  • the ADFS service communications certificate, and
  • the ADFS SSL certificate

The first step is to replace the service communication certificate. After importing the certificate with private key, you need to assign “read” permission to the ADFS service account. Right click on the certificate, then “All Tasks” > “Manage Private Keys”.

Make sure to import the certificate on all farm servers! Next step: Start the ADFS management console on the primary node. Select “Certificates” and then “Select service communication certificate” on the right window pane.

Now we have successfully replaced the service communication certificate. But we are no finished yet! Now we have to set the ADFS SSL certificate. Depending on your OS, you have to run the PowerShell command on the primary node. If your are running Windows Server 2012 R2 or older, you have to run the PowerShell command on EVERY ADFS farm server!

You can get the certificate thumbprint using the Get-AdfsSslCertificate command. Set the ADFS SSL certificate with

Set-AdfsSslCertificate -Thumbprint 07B3DFE31E020BFC3F3BDF1A0F61807223DBF125

Then restart the ADFS service.

Restart-Service adfssrv

ADFS Proxies

In most cases you will have one or more ADFS proxies in your DMZ. The ADFS proxy is nothing more than a Web Application Proxy (WAP) and therefore the PowerShell commands for WAP will be used.

First of all: Import the new certificate with the private key on all ADFS proxies, and then get the certificate hash of the new certificate. Then open an elevated PowerShell on each proxy.

Set-WebApplicationProxySslCertificate -Thumbprint 07B3DFE31E020BFC3F3BDF1A0F61807223DBF125

Then we have to re-establish the trust between the proxies and the primary ADFS farm server. You will need the local (!) administrator account of the primary farm server.

$cred = Get-Credential
Install-WebApplicationProxy -FederationServiceTrustCredential $cred -CertificateThumbprint 07B3DFE31E020BFC3F3BDF1A0F61807223DBF125 -FederationServiceName adfs.domain.tld

The last step is to update thefederated trust with Office 365.

Update the federated trust with Office 365

To update the federated trust with Office 365, you will need the Windows Azure Active Direcotry Module for Windows PowerShell and an elevated PowerShell. Connect to Office 365 and update the federated trust:

$cred = Get-Credential
Connect-MsolService -Credential $cred
Update-MSOLFederatedDomain –DomainName domain.tld

That’s it! Bookmark this page and set a calendar entry on today +12 months. :)

Missing Microsoft Teams calendar tab with on-premise Exchange

Microsoft Teams got a big push due to the current COVID19 crisis and many of my customers deployed it in the past weeks. At ML Network, we are using Microsoft Teams for more than a year, and we don’t want to miss it anymore.

Source: Microsoft

We are running Exchange 2016 on-premises, currently CU16. We were missing the calendar tab in Teams since we started with Microsoft Teams. when you do some research about this issue, you will find many threads and blog posts, but these are the two key facts:

  • it is supported with on-premises hybrid Exchange deployments
  • it works flawless with Exchange Online

Our Exchange is configured as full-hybrid mode deployment. I did this as we deployed Office 365 at our organization.

Let’s summarize:

  • Exchange 2016 CU16
  • Hybrid Deployment
  • Office 365 with Teams enabled
  • no calendar tab when the Exchange mailbox is hosted on-premises

OAuth FTW!

While doing an Exchange Hybrid deployment for one of my customers some weeks ago, I’ve stumbled over an OAuth error message at the end of the Hybric Connection Wizard. The message was HCW8064

“HCW has completed, but was not able to perform the OAuth portion of your Hybrid configuration”

We were not able to fix this. Microsoft offers two solutions:

Yesterday I did the upgrade from CU15 to CU16 on our Exchange server and while watching the progress bar I did some research on this issue again. I found strong evidence that Microsoft Teams needs working OAuth to display the calendar tab and access the on-premises hosted mailbox. So I gave it a try and used the latest version of the HCW wizard.

What should I say? No OAuth configuration error and after a restart of Microsoft Teams, the calendar tab appeared.

Lessons Learned:

  • always use the latest CU für Exchange
  • always use the latest HCW Wizard

Connecting to Exchange Online with PowerShell

The task was simple: Change the alias and the primary SMTP address of a Microsoft Teams team. This can be done by changing the alias and the SMTP address of the underlaying Office 365 group. But how? All you need is a PowerShell connection to Exchange Online.

All you need is a PowerShell on your local computer and Office 365 credentials with the necessary privileges.

First we need to provide the necessary credentials.

 $cred = Get-Credential

A windows will come up and you must enter your Office365 credentials.

The next step is to create a PowerShell remote session with Exchange Online.

$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $cred -Authentication Basic -AllowRedirection

Please note that basic auth will be disabled in October 2020!

To connect to this remote session, use Import-PSSession.

Import-PSSession $Session -DisableNameChecking

When you finished your work, make sure to remove the remote session with Remove-PSSession!

Remove-PSSession $Session 

Choose one, choose wisely – Office 365 tenant name

This posting is ~3 years years old. You should keep this in mind. IT is a short living business. This information might be outdated.

In the last months I came across several customers that were in the process to evaluate, or to deploy Office 365. It usually started with a Office 365 trial, that some of the IT guys started to play around with. Weeks or months later, during the proof-of-concept or during the final deployment, the customer had to choose a Office 365 tenant name. That is the part before .onmicrosoft.com.

Office 365 User ID Creation

Patrick Terlisten/ www.vcloudnine.de/ Creative Commons CC0

I had it multiple times, that the desired tenant name was already taken. Bummer. But the customer wants to move on, so the customer decided to take another another name. For example, they added the post code to the name, or a random string. To their surprise, I put my veto on it. They immediately understood why, after I explained the importance of the tenant name.

The tenant name is visible for everyone

When using Sharepoint or OneDrive for Business, the Office 365 tenant name is part of the URL to access the service. Due to this, the tenant name is visible for everyone, including your customers. And no one wants to click on a link that points to noobslayer4711.onmicrosoft.com.

How to build a good tenant name

When thinking about the tenant name, make sure that you involve all necessary people of your company. Make sure that the management and marketing have agreed, when you recommend a specific tenant name.

Don’t use long names, or tenant names with numbers at the end. They might look suspicious and randomly generated. Make sure, that the tenant name does not include parts that might change in the near future, for example the legal form of your company.

Don’t add the current year, month or a date to it. Don’t add things like “online” or “24” to it, except it’s part of the companies name.

If you have created a tenant during a trial or during a proof-of-concept, try to reactivate it, especially, if the tenant uses the desired name.

Currently, you can’t change the Office 365 tenant name. I don’t know if Microsoft plans to make this possible.

How to reclaim a tenant name

As far as I know there is no process for reclaiming a tenant name instantly. When the last subscription of a tenant expires, the tenant becomes inactive. After 30 days, the tenant will be decomissioned. But it takes several months, until a tenant name can be used again.

As I said: Choose one, choose wisely…