Can’t Connect Outlook 2003 To Exchange 2010. Unable To Open Your Default E-mail Folders

MS Exchange

I was trying to connect to my Exchange 2010 RC Server with Outlook 2003, but couldn’t connect successfully. I tried with Outlook 2007 & 2010 and was able to connect successfully. That made me search whether Outlook 2003 is a supported client and it is. The error message is “Unable to open your default e-mail folders”

After playing around for a while, I found the solution. Before I jump in to the fix, let me explain a few changes in Exchange 2010 in terms of MAPI connectivity.

  • All MAPI clients connecting to Exchange 2010 server connects to the mailbox through the CAS Server.
  • A new service named Exchange RPC Client Access is introduced in 2010 CAS which handles all MAPI connections.
  • All MAPI clients connect to the mailbox server directly in Exchange 2007.

Now that we know about the new RPC Client Service running on the 2010 CAS Server, lets bring up the full info by running Get-RpcClientAccess | fl

We can see that this service needs rpc encryption and it is set to True by default.
Same is the case with Outlook 2007 & 2010 profiles! Encryption between Outlook and Exchange is enabled by default, which explains why these clients can connect to Exchange 2010 without any issues.
Outlook 2003 profiles don’t enable encryption by default.
Once I checked the box, I could connect to my 2010 mailbox.
You can also disable the requirement of 2010 CAS servers to have encryption enabled by running Set-RpcClientAccess –server servername –EncryptionRequired $false. This is not recommended though!
If you have too many Outlook 2003 clients trying to connect to a 2010 server, you can enable encryption using Group Policy.

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  1. Thanks for this, was stumped for a while. We have ONE Outlook 2003 user left out of around 300 staff. He’s a director though. Much appreciated.

  2. I cannot find those settings to check that box… my Outlook closes automatically after the error how am I supposed to find this option to check it?

    • Hi Jason,

      Don’t fully configure the profile. Set the server name etc and click on “More Settings”, before clicking “Next.

  3. This was just what I needed to hear this morning after moving mailboxes to Exchange 2010 last night for our users.

    The solution worked fine, except for the Office XP user, of which I’ve only found one so far.

    I’ve moved their mailbox back to the 2003 server for now, until I can upgrade their Office install.

    Thanks Alot


  4. Hi,

    Doesn't the policy tell you the clients supported? You can see that normally at the bottom of the window, when the option is double clicked.

    Isn't non-OutlookSP3 machines getting the policy? Or is it the OS service pack? Does it work if you manually enalbe one of the clients?


  5. I just migrated my exchange server to 2010. Clients are running a mix of outlook 03/07. Everyone on outlook 07 is working but only the machines that are less then 3-4 years old are getting the policy. Is there any prerequisites (such as SP3) for this to work. There are about 2500 computers in my company and around 400 are having this problem so help will be greatly appreciated.

  6. helpful post – put in a new Exchange 2010 box over the weekend, all my 2007 clients were fine, but my one 2003 client was not. This past was first on google and extremely helpful

  7. To answer Deepak's question on CASArray, you need to create a DNS record for the name that will be CASArray, you also need to either use hardware load balancer and point the name you created in step above to the hardware load balancer IP. If you choose to use Windows NLB instead, you will need to configure it on all CAS servers that will participate in array and assign it a unique IP. Using the cmdlet to create CASArray just tells CAS servers that an array exists. It does not work until you actually setup that array by using hardware or windows NLB.

  8. Hi Rajith,
    Thank you very much, this was my exact error and solution.
    You might want to indicate that Outlook 2003 can still access Exchange 2003 server mailboxes with encryption checked so a GP could be rolled out before mailboxes are moved without affecting connectivity.


  9. Hi Rajith,

    I made it work, you have to be really careful when copying the text of the microsoft article because i always was getting the error when importing the administrative template there was a problem at line 16.


    CATEGORY "Outlook 2003 RPC Encryption"
    CATEGORY "Exchange settings"

    POLICY "Enable RPC Encryption"
    KEYNAME SoftwarePoliciesMicrosoftOffice11.0OutlookRPC
    PART "Encrypt data between Microsoft Office Outlook and Microsoft Exchange" CHECKBOX
    VALUENAME EnableRPCEncryption


    Also i forgot to replicate to my DC who was in another site that i used for testing. My users running outlook 2003 now have the encryption option enabled by default and are not allowed to change it. It also works fine on our terminal servers.

    Much thanks,


  10. This may sound stupid, but I can't configure my clients to receive the new security settings. I even followed this microsoft article: When I gpupdate /force my client to receive the new GPO, it changes his security settings but the checkbox in outlook – encryption isn't ticked?

    Have any of you already implemented this using GPO's or used another way to do this?

    My client runs win xp sp3 with outlook 2003.


  11. Hi Rajith

    I was playing around with client connectivity and found that the Outlook 2007 do not automatically failover to active DAG Mailbox database server.

    I found the cause of it, the MAPI client connect to the perticular CAS based upon a attribute "RPCclientAccessServer" in mailbox database property, which is set statically when the mailbox database is created.

    Now you would expect that when active mailbox database fails, you will update the RPCClientaccessserver property in the database but that does not happen.

    Even worst when you have one mailbox server (NO DAG) and 2 CAS server (on seperate server to mailbox), when you create a database it will set RPCclientaccessserver to one of the CAS server and if that server is unavailable for any reason, the client will disconnect and will not failover to onother cas server.

    Looking around in web I found that you need to create a ClientAccessArray. using the powershell script

    New-ClientAccessArray -Fqdn -name -site sitename

    Even after creating this array which include both of CAS server in the environment, it does not do much.. I think there is still some bug in Exchange 2010 related to ClientAccessArray which is not working as expected.

    I even try to set the RPCclientAccessserver property to name of CLientaccessarray but that does not work since OUltook client will not be able to resolve the Clientaccessarray name.

    I guess New-Clientaccessarray is not doing its job by creating a NLB on both the CAS Box and creating necessary DNS records. Not much documentation is provided on ClientAcessArray by MS yet.

    As I mention in my earlier post, moving MAPI client to CAS server does require more planning and configuration..

    I wounder how Outlook 2010 client works in this case?

    Hope MS will resolve this in RTM..

  12. Great article.. thanks for sharing

    In Exchange 2010, Outlook will be connecting to CAS which will atleast go with its name Client access server covering all types of clients

    But it does introduce one more problem with placing the cas role in the environment, now we will need CAS, hub and mailbox role in each site where there is mailboxes.. Not a big deal but it does require some planing for external owa connectivity in larger environment since you do not want external connection to each CAS server in the environment. It some environment, they might need didicated CAS for OWAactivesyncRPC-http with loadbalancing as in exchange 2007.

    May be it is better to have Mailbox and CAS role together (acting similar to Exch 2007 for outlook) and have HUBCAS role additional for external connectivity.

    I would be intrested to know how does outlook client determines which cas to use and how it is loadbalanced? Also by having outlook connection through CAS what are the sizing requirement to handle the load, does that means that you we need more CAS then mailbox server (since it act now more like database server)?



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Disable Windows Copilot Using Intune

Windows Copilot is Microsoft’s take on making life easier for Windows users using the power of AI. This article explains how to disable the feature using Intune, if your organization is not ready yet to walk into the AI world.

Disable Windows Copilot Using Intune

We need to create a Configuration Profile for Windows devices in the Intune portal to disable Windows Copilot. Below are the steps that we need to create the profile.

Launch the Intune Portal and login as a Global Admin or Intune Admin.

Navigate to Devices -> Windows -> Configuration Profiles.

Windows Configuration Profile Intune

Click on Create -> New Policy.

Select Windows 10 & later as the platform and Settings Catalog as the profile type & click on the Create button.

Settings Catalog Intune CoPilot

Give the policy a meaningful name & description and click Next.

Policy Name Disable CoPilot

Within the configuration settings, click on the Add Settings option.

Add Settings Disable CoPilot

Search for ‘copilot’, Windows AI will come up as the category. Click on Windows AI and the Turn off Copilot in Windows (User) setting will come up. Check the box and click Next.

Turn off CoPilot Setting Intune
Turn off CoPilot Setting Intune Summary 1

Specify scope tags if required and click Next.

Select tags CoPilot Intune

Select who this policy should apply to in the Assignments section. I have selected to add all users. If you want to test the setting, you can create a test group and select that group here.

Similarly, you can also exclude certain group from disabling AI (say IT team) if required.

Add all users disable copilot intune

A summary of selected settings will be displayed. Click on the Create button to setup the policy to disable Windows Copilot.

Create configuration policy disable CoPilot Intune 1

Wait for the replication to complete in the cloud backend and login to your machine. Your chatty Copilot should now be disabled.

Disable Windows Copilot On Windows 11 Pro

Follow the steps below to disable Copilot on a personal Windows 11 Pro machine (say your own laptop).

Search for ‘group’ in Windows 11 and click on Edit Group Policy option.

Group Policy Windows 11 Disable Copilot

Navigate to User Configuration -> Administrative Templates -> Windows Components -> Windows Copilot.

Windows Copilot GPO setting

Double click on Turn off Windows Copilot setting on the right pane.

Select Enabled and click OK.

Turn off copilot gpo Windows 11 Pro 1

Close the Group Policy Editor. This will disable Windows Copilot on a Windows 11 Pro machine.


We have learned to disable Windows Copilot using Intune and Group Policy on Windows 11 machines.

Please let me know if you have any questions in the comments section.

Promote Windows Server 2025 To Domain Controller

Domain controllers are the backbone of any Active Directory domains in the Microsoft world. Any Windows server can be promoted to be a domain controller. In this article, we will go through the steps of promoting a Windows 2025 Server to be a domain controller.

Windows Server 2025

The latest version of the server operating system has been named Windows Server 2025. You can start with a 2025 Server & create an AD domain or you can promote a member server that is already a part of a domain.

The Windows Server 2025 needs to be installed on a machine before it can be promoted to be a domain controller.

Promote Windows Server 2025 To Domain Controller

If you have been working with Windows servers long enough, everything starts with the Server Manager app. Promoting a server to a domain controller is no different.

Launch ‘Server Manager’ & click on Add roles and features.

Windows 2025 Server Manager

You land on the summary page that explains what is required to run this wizard successfully. Click Next.

Windows Server 2025 Add Remove Roles

Select Role-based or Feature-based installation and click Next.

Windows Server 2025 Role Based Install

Select the server that needs to be promoted and click Next.

Windows Server 2025 Destination Server

Select Active Directory Domain Services (second option) and click on Add Features.

Windows Server 2025 AD Domain Services

Go with the default options for features that need to be installed.

Windows Server 2025 AD Domain Services Features

A summary of AD DS pops up next, click next to continue.

Windows Server 2025 AD DS

Select Restart the server automatically if required and click Install.

Windows Server 2025 AD Restart Server

You get to keep an eye on the progress of the installation.

Windows Server 2025 AD Install Progress

Once the role has been installed, you will find an exclamation mark on the top right corner of the Server Manager. Click on that and select Promote this server to be a domain controller.

Windows Server 2025 AD Install Continue

You get an error straight away (which you have never seen before) – Error determining whether the target server is already a domain controller. Role change is in progress or this computer needs a restart.

Windows Server 2025 Domain Controller Setup Error

We never needed to restart the server after installing the role in the DC promotion process. Given that it is an insider build of Server 2025, I am hoping that this will get fixed before the public release.

Restart the server, launch Server Manager and click on the Promote this server to be a domain controller option again.

Windows Server 2025 AD Install Continue 1

I am setting up a brand new AD forest and hence I select the third option (Add a new forest) and enter my root domain name.

Windows Server 2025 Add a forest

Next window brings the option to set your forest & domain functional level and the DSRM password. In the insider build, it shows what looks like a variable (the Windows server version on which the you are working).

Windows Server 2025 Forest Functional Level

You can leave the default options in the DNS options wizard and click next.

Windows Server 2025 DNS Options

Enter the netbios name of the domain in the next window and click next.

Windows Server 2025 Netbios Domain Name

You can stick with the default paths for the AD database, log & sysvol folder or pick a location of your choice.

Windows Server 2025 AD Paths

Review the selections that you have made so far and click next.

Windows Server 2025 Options Review

Wait for the green check mark on the prerequisites page and click next.

Windows Server 2025 Pre reqs Check

Click Install in the final window & wait for the magic to happen. Once the machine gets restarted (which it will do automatically), you will have a brand new domain controller based on Windows Server 2025.

Windows Server 2025 AD Snap In


Promoting a Server 2025 to a domain controller follows pretty much the same steps as previous operating systems. The Insider build has few errors that needs to be fixed, but hey, it is an insider build!

Please let me know if you have any questions in the comments section.

Install Windows Server 2025 – Full Guide

Microsoft has released an insider preview of it’s next server operating system named Windows Server 2025. We will have a look at the installation steps involved in setting up a 2025 server.

Windows Server 2025

Microsoft has gone with the same look and feel of Windows 11 operating system in it’s current server operating system – Windows Server 2025. As the product is in insider preview, there might be slight changes before it hits the public shelves.

It is refreshing to see a ‘modern’ feel in the installation process of a server operating system. Gone are the days where the installation of a consumer based OS felt much better compared to it’s server counterpart.

Installing Windows Server 2025

Let’s take a look at the steps involved in setting up a Windows Server 2025 machine. First step is to download the ISO from the Windows Insider portal.

Next step is to boot the virtual / physical machine from the ISO which will kick off the installation of Server 2025.

First option to select is the language settings. Pick the one based which relates to you and click next.

Windows Server 2025 language settings

Select the keyboard settings in the next screen and click next.

Windows Server 2025 keyboard

You get the option to select whether you want to Install Windows Server or Repair the installation. The bottom left corner also has the option to go to the previous version of setup.

Windows Server 2025 setup option

You are asked to enter the product key, which is available in the Windows Insider portal.

Windows Server 2025 product key

Next option to choose is the type of image you want to install – Windows 2025 core or full blown desktop experience.

Windows Server 2025 Desktop

You need to agree to the licensing terms to move forward in the next step.

Windows Server 2025 Agreement License

Select the partition on which the server OS should be installed and click next. You also have the option to slice the partitions the way you see fit in the same screen.

Windows Server 2025 Disk Partitions

The Ready to Install window comes up, click the install button.

Windows Server 2025 Install 1

Installation of Server 2025 is underway and you get to see the progress.

Windows Server 2025 Install Progress

Once the installation is complete, you need to enter an administrator password of your choice to finalize the setup.

Windows Server 2025 Password

And there you go! You see a Windows 11 login screen staring at you ;-)

Windows Server 2025 Login Screen

After logging in, you get to set the options around sending diagnostic data to Microsoft, which I always set as ‘required only’.

Windows Server 2025 Diagnostic Data

The Windows Server 2025 desktop looks similar, doesn’t it? ;-)

Windows Server 2025 Desktop Feel scaled

Now that the server is up and running, you can promote it to be a domain controller.


The Windows Server 2025 has the same look and feel as a Windows 11 operating system. The installation options also provide that modern ‘feel’ and makes it a bit soothing to the eyes!

Please let me know if you have any questions in the comments section.