MVP - Most Valuable Professional

Just can't get enough of IT

This blog is about mostly anything in IT. But the primary focuses are Microsoft technologies like Exchange Server, Microsoft 365, Microsoft Teams, and Cloud Security.

When you move mailboxes using migration batches you might encounter a situation that your batch contains migration users that fail during batch execution. One of the possible reasons is an existing move request for the affected users. You must remove those requests to successfully move mailboxes.

The following PowerShell example gets all failed migration users from a migration batch and removes existing move requests. 

$r = Get-MigrationUser -BatchId MyMigrationBatch | ?{$_.status -eq 'Failed'}
$r | %{Remove-MoveRequest -Identity $_.MailboxIdentifier -Confirm:$false}


Enjoy Exchange Server!


Read More »

These are the results of the  Exchange Server Questionnaire from August 2021.

First of all, I want to thank all of you who participated in the questionnaire. The results are pretty interesting. Even though, that the results are not 100% representative they provide a high-level view of the Exchange Organizations, the mail flow configurations, and the future plans regarding hybrid and Exchange Online.

With 55 replies the questionnaire is far from being a comprehensive representation of the Exchange organizations. But the answers provide an idea of the Exchange landscape used by organizations globally.


1. Exchange Server Versions in use (Production)

Exchange Server 2016 is the dominant version currently in use, followed by Exchange Server 2019. The vast majority of 93% runs modern Exchange Server versions. But there are still older and unsupported Exchange Server versions in use. 7% use Exchange Server 2010 and older. 


Diagram Exchange Server Versions in use (Production)


2. How many Exchange Server systems do you operate?

76% of the organizations maintain up to ten Exchange servers. 20% prefer to rely on just one Exchange server. It is interesting that only 2 (not percent) plan to go hybrid or to move to Exchange Online.  


Diagram How many Exchange Servers do you operate?


3. How many mailboxes do your Exchange Servers host?

The majority of on-premises Exchange organizations are in the 1,000 - 10,000 mailboxes range. Nevertheless, the SMBs with 1 to 1,000 mailboxes adds up to 50% of the Exchange organizations that took part in this questionnaire. There are just a few organizations that host more than 50,000 mailboxes.    


Diagram How many mailboxes do your Exchange Servers host?


4. Do you use an on-premises or cloud-based SMTP gateway solution?

There are Exchange organizations that do not use an SMTP-Gateway solution as part of the mail-flow implementation. Thor organizations that do not use a gateway solution run 1 to 10 Exchange servers on-premises. The majority of those have less than 1,000 mailboxes but there are a few that are responsible for more than 1,000 mailboxes. That leaves the question of why an organization prefers to not secure mal-flow with a gateway.


Diagram Do you use an on-premises or cloud-based SMTP gateway solution?


5. Which product do you use as a gateway solution?

The use of SMTP gateways is a must, as you do not want to expose your domain member servers to the Internet, not even for the SMTP protocol. A majority of 28 answers for other gateways shows, that there are so many products available and that I did not choose valid answer options upfront. 


Diagram Which product do you use as a gateway solution?

The Other answers include:

  • Cisco ESA
  • Clearswift
  • Eleven
  • Fortigate
  • IronPort
  • Postfix
  • Reddoxx
  • Trustwave


6. Is your current Exchange organization using a hybrid configuration with Exchange Online?

65% of the Exchange organizations of this questionnaire already run in a hybrid configuration with Exchange Online. Only 35% are (still) not using a hybrid setup.  


Diagram Is your current Exchange organisation using a hybrid configuration with Exchange Online?


7. Do you plan to implement a hybrid Exchange configuration or to move to Exchange Online?

Of those who currently do not run a hybrid configuration only 37% plan on implementing Exchange Hybrid or migrate fully to Exchange Online. Staying on-premises is the only option.


Diagram Do you plan to implement a hybrid Exchange configuration or to move to Exchange Online?


8. Until when do you plan to implement a hybrid configuration or go cloud-only?

The majority of the organizations still running only an on-premises Exchange organization plan on implementing Exchange Hybrid or migrating to Exchange Online by the end of 2021. None of the participating organizations has plans scheduled after 2022.

Diagram Until when do you plan to implement a hybrid configuration or go cloud-only?


9. Which hybrid model did you choose?

It is no surprise that Classic Full Hybrid is the most adopted hybrid configuration. And, no surprise either, none of the other classic hybrid options is implemented. The modern hybrid approach is implemented but with lesser.

Diagram Which hybrid model did you choose?


10. What are the reasons for staying 100% on-premises?

The reasons for staying with an on-premises Exchange organization vary. the reasons mentioned are:

  • Enclosed environment, external access with BlackBerry UEM, due to public sector data security requirements
  • Mailbox data is classified as too sensitive
  • Too expensive and low internet bandwidth
  • Legal and clients audits 

There are still organizations that choose an on-premises Exchange organization in favor of Exchange Online. I wonder if company policies for reducing the carbon footprint might drive the migration of on-premises data center resources to hosted cloud services.  


11. Will you implement Exchange Server vNEXT?

Exchange Server vNEXT is in scope for 47% of the organizations. When comparing it with the used Exchange Server version currently in use (~50% Exchange Server 2016) it is an indicator that some companies just skip Exchange Server 2019. Some organizations prefer not to follow the full life-cycle of Exchange Server. s7% of those who do not want to implement Exchange Server vNEXT and want to stay on-premises are single server implementations of Exchange. 

Diagram Will you implement Exchange Server vNEXT?




The product Exchange Server is still widely used in on-premises deployments. The reasons vary from legal and compliance requirements, network bandwidth constraints, and the overall costs for Exchange Online. Exchange Server vNEXT is a must-have for nearly 50% of the organizations participating in this questionnaire. There are still older and unsupported versions in productive use. Why this is the case is unanswered in this questionnaire.

Organizations running a hybrid Exchange configuration primarily use a Classic Full Hybrid configuration. This might be due to an early implementation in those days when nothing else was available, or due to requirements using Microsoft Teams with on-premises mailboxes. The adoption of Modern Hybrid shows that the Hybrid Agent approach helps organizations that cannot implement a Classic Full Hybrid. 

I leave the results of this questionnaire to your interpretation and look forward to your replies, either to this blog post or by social media on Twitter and LinkedIn. Please use the hashtag #ExchangeQuest2021.

There will be a new Exchange Server questionnaire in early 2022, covering various implementation scenarios in more detail. If you want to see a specific Exchange topic covered in the 2022 questionnaire, just let me know.

Again, thank you all for participating in this questionnaire.



Read More »

You might see the following error in the Windows Application Event Log:

  • Source: MSExchangeApplicationLogic
  • Event ID: 3018
  • Level: Error
The request failed. Mailbox:  

System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a send. 
---> System.IO.IOException: Unable to read data from the transport connection: 
   An existing connection was forcibly closed by the remote host. 
---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host
   at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult)
   at System.Net.Sockets.NetworkStream.EndRead(IAsyncResult asyncResult)
   --- End of inner exception stack trace ---
   at System.Net.TlsStream.EndWrite(IAsyncResult asyncResult)
   at System.Net.ConnectStream.WriteHeadersCallback(IAsyncResult ar)
   --- End of inner exception stack trace ---
   at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
   at Microsoft.Exchange.Data.ApplicationLogic.Extension.BaseAsyncOmexCommand.<>c__DisplayClass18_0.<EndGetResponseCallback>b__0()


Screenshot - Event log MSExchangeApplicationLogic Event ID 3018

The request is successful when you try to connect to the URL provided in the error details using a browser on the Exchange server. 



You can verify that the issue by trying to access the URL using the PowerShell Invoke-WebRequest cmdlet. Open a new PowerShell session and try connecting to the URL.


Invoke-WebRequest -Uri $uri

You will receive the same error message as stated in the event log by MSExchangeApplicationLogic. A successful connection returns XML as content.

The reason for this error is related to the .NET Framework TLS configuration, not Exchange Server. The .NET Framework lacks configuration for the use of TLS 1.2.



The solution for this issue is to configure the .NET Framework to correctly use TLS 1.2. You can follow the description for TLS 1.2 enforcement for Azure AD Connect, or you can simply use this Gist

Due to the changes made to the SCHANNEL configuration you just restart the computer to bring the changes into effect.


Changing the TLS settings does not only affect outgoing connections but incoming connections as well.

Test the TLS changes in a test environment before adjusting your servers in the production environment. If you have not already enabled TLS 1.2 for your Exchange Servers, I recommend reading the 3-part series by the Exchange product group.




Enjoy Exchange Server! 




Read More »

IllustrationThe Problem

Mail flow from on-premises devices and applications to Exchange Online is a tricky topic. The documentation allows for different solutions.

Recently a client ran into a situation where an on-premises application was not able to deliver messages to a configured inbound connector in the Exchange Online tenant. The connector was configured for remote IP address selection.

Exchange Online responded to each connection attempt with the following error message:

  • 451 4.4.3 Temporary server error. Please try again later ATTR3.1

There weren't any changes on the on-premises configuration and the setup was in use for multiple months without any issues.


The Solution

It took some time to identify the solution, but in the end, the solution was easy.

Disabling and re-enabling solved the issue.  


Enjoy Exchange Online.


Read More »

Exchange Server 2019 LogoThe Problem

You might face a situation during an Exchange Server migration where your Exchange Server 2019 mailbox users are not able to open their public folder favorites when using Outlook on the Web (OWA).

When your users try to access a public folder, they receive an error message.

Screenshot Public No Folders available


This error occurs when the public folder mailboxes are still hosted on a previous version of Exchange Server. This includes Exchange Server 2016 and 2013.

The online documentation explains, why this is happening:

  • Access public folders located on servers running previous versions of Exchange


The Solution

The solution to this problem is easy. Move the public folder mailboxes to Exchange Server 2019 before you migrate any user mailboxes. 

This approach ensures that mailboxes hosted on Exchange Server 2019 and previous versions of Exchange Server are able to access public folders using Outlook on the Web.




Enjoy Exchange Server.



Read More »