Exchange 2010 and Outlook 2003 clients - connection issues
Having a hard time connecting to an Exchange 2010 mailbox using an Outlook 2003 client?
Here’s the deal. So as most of you already know Exchange 2010 introduces a new client access service named RPC Client Access. This service lives on the Client Access Server (CAS) and allows MAPI clients (Outlook) to connect to a CAS server just like pretty much all the other Exchange clients do nowadays (with WebDAV deprecated in Exchange 2010, even Entourage clients will need to connect to the CAS).
This means that Outlook clients no longer connect directly to an Exchange 2010 Mailbox server. Well, at least not when we’re speaking mailbox access (public folder connections will, after being authenticated by the RPC Client Access service on the CAS, be directed to the Mailbox server).
One of the default settings for the RPC Client Access service is that it requires encryption for RPC connections. You can check this setting using the following command: Get-RpcClientAccess | fl
This is not an issue if you use Outlook 2007 or Outlook 2010 since these Outlook versions have RPC encryption enabled by default, when you create a new Outlook profile, see below:
But guess what? Yes the old Outlook 2003 version behaves differently. You see, when you create a new Outlook 2003 profile, RPC encryption is disabled by default in this client version.
This means that if you migrate an Exchange 2003 or 2007 mailbox to Exchange 2010, or try to create a brand new Outlook 2003 profile against an Exchange 2010 mailbox, you won’t be able to connect to the mailbox. After authentication, you will instead receive a dialog box similar to the below (click on it to see it in full size):
The issue can be resolved in two ways. You can either enable RPC encryption in the Outlook 2003 profile (if you have many, you could do so via a GPO) or disable the RPC encryption requirement on the Exchange 2010 Client Access server. Enabling RPC encryption on the client is of course the recommended over disabling it server-side. If you insist on disabling this setting server-side, you can use the following command:
Set-RpcClientAccess –Server –EncryptionRequired $false
As you can see by running Get-RpcClientAccess | fl, the encryption requirement is now disabled, and you will be able to connect to your Exchange 2010 mailbox using Outlook 2003 clients that doesn’t have RPC encryption enabled (default mode).


Weekend Nieuws | Ward Vissers Says:
September 5th, 2009 at 11:16 am
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Henrik Walther Blog » Blog Archive » Exchange 2010 RPC Client Access arrays and Outlook 2003 Says:
September 10th, 2009 at 6:35 am
[…] For details on how you disable RPC encryption server-side, see this previous blog post of mine. […]
Kelvin Vanderlip Says:
November 8th, 2009 at 3:42 am
Thanks for this encrypted-RPC hint. Funny how I had to find it here - I searched the Microsoft site for a while without any success. It must be buried there somewhere, right?
Scrooge McDuck Says:
November 30th, 2009 at 5:59 am
This is all we get, what did we miss???
PS C:\Users\administrator.ourNET> Set-RpcClientAccess -Server scrooge -EncryptionRequired $false
The term ‘Set-RpcClientAccess’ is not recognized as the name of a cmdlet, function, script file, or operable program. C
heck the spelling of the name, or if a path was included, verify that the path is correct and try again.
At line:1 char:20
+ Set-RpcClientAccess
DThimsen Says:
January 4th, 2010 at 8:42 pm
We didn’t have any problem connecting Outlook 2003 clients to Exchange 2010, however we are having interface problems with 2003 clients that do not use Cached Exchange Mode. When users delete items from folders, outlook doesn’t seem to refresh the item list. If you try and delete the item again, outlook throws an “unknown error” message. If you delete an item and then navigate away from a folder or even use the navigation pane to display the same folder, the item list will refresh and remove the deleted message.
We’re seeing this on all Outlook 2003 sp3 clients. Any ideas?
G-Man Says:
January 25th, 2010 at 11:59 am
@DThimsen
Did you fix this prob.?? …. we have the exakt same this going on with out 2003 clients i non-cached mode.
best regards
SvH Says:
February 22nd, 2010 at 8:45 am
We have also the same problem with outlook refresh und “unkown error” message. Has anyone a solution? We have Outlook 2003 SP3 and Exchange 2010 with rollup 1.
Mark Gerlow Says:
March 11th, 2010 at 1:42 am
I\’ve just started to upgrade a customer, and they have the excact same problem. really annoying. Anybody have a solution?
Rick Says:
March 23rd, 2010 at 10:49 am
Having the same problem with outlook 2003 clients connected to exchange 2010. Deleting emails does not seem to refresh and when users try to delete them again they get unknown error. Navigating to another folder and back and the deleted emails are gone. Really annoying.
Patrick Hoban Says:
April 21st, 2010 at 7:39 pm
I too am having the issue with Outlook 2003 not refreshing after a delete. Since it doesn’t refresh & you try to delete the message again you get the “Unknown Error” message. I’ve notice that if you delete the message then let it sit, the view will refresh at exactly 1 minute.
Ewan Says:
April 21st, 2010 at 8:05 pm
Having the same issue, anyone found a fix?
Ewan Says:
April 21st, 2010 at 9:41 pm
apparently, you install the update rollup.
After you install the update, which speeds up the refresh a bit, you can add the following registry data to the server by using the Client Access role.
Start Registry Editor.
Locate and then click to select the following registry subkey:
HKEY_LOCAL_MACHINE\CurrentControlSet\Services\MSExchangeRPC\ParametersSystem
Note Create the \ParametersSystem registry subkey if it does not exist.
Add the following registry data to the server:
Value type: REG_DWORD
Value name: Maximum Polling Frequency
Value data: any integer between 5000 and 120000 (decimal value)
Exit Registry Editor.
I haven’t tried this yet but will tonight.
Luis Says:
August 4th, 2010 at 11:04 pm
hi everybody
I have outlook 2007 in trying to connect with outlookanywhere with EncryptionRequired enabled but still cannot access my mailbox ……anyideas whats wrong?
Thanks
Alex Says:
September 22nd, 2010 at 6:03 am
Ewan,
where can I find the update - I’m also experiencing the deletion problem.
Thanks
Jason Says:
January 24th, 2011 at 10:12 am
After a 48 hour migration this past weekend we got bit by this Monday morning. Thanks to this post we had everything up and working by 10am.
Rita Says:
January 28th, 2011 at 7:16 am
I am also havin the problem of 2003 outlook clients having connectionn issues since the upgrade to exchange 2010. I already have the the encryption required set to false. users are experiencing connect and disconnect’s, Mail not leaving the outbox and some issues with users opening shared calendars. They can use OWA without a problem. Any help would be appreciated.
Thanks Rita
Frank Bicocchi Says:
February 10th, 2011 at 3:19 pm
I had just performed an exchange 2003 to exchange 2010 migration. First off, this went flawless! I was so happy with the outcome. As many of you know, Exchange 2010 requires 64 bit OS. THEREFORE, I started the projected by creating a new 64-bit Windows 2008 enterprise server and a new windows 2008 64 bit enterprise domain controller in an existing 2003 active directory environment. First, let me say that you have to run adprep off the 2008 cd on your DC that holds your fsmo roles. I installed exchange 2010 and brought up a new BES 5.0.2 server as I thought this would be an excellent time to refresh corporate blackberry users. I love this version of exchange! I was running co-existence mode until the migration was complete and then I uninstalled exchange 2003 from my environment and retired that old clunky exchange server. Let me say that despite the noise about making your client access and mailbox role a VM. I had no issue doing this, as I am a huge VMware and virtualization fan. I have had no issue with my cas, hub, and mailbox roles all in one VM with zero performance issues. One thing I do not like is that by design store.exe is now a memory hog! However, there are parameters that you can use in adsiedit.msc where you can limit the memory usage of store.exe that work great! All in all the only complaint I got was from the helpdesk, as they cannot install Exchange management tools on their desktops because they run 32 bit OS. I told them to upgrade their desktop OS to 64 bit so they can run the tools. I know they make some third party management tools that allow your helpdesk to still perform common exchange tasks but I am NOT a big third party fan. If anyone has any questions about more details about my migration from exchange 2003 to 2010 I will be more than happy to answer them. In addition, when you plan your exchange 2010 rollout one big thing to remember here is give yourself plenty of space for the info store lun as exchange 2010 does NOT like to have less than 2 gb free space of the store lun or luns. If it goes below 2 GB mail will stop flowing and will not flow again until you free up some space.
Frank Bicocchi
David Says:
February 17th, 2011 at 3:27 am
Having the same issues with Outlook 2003 (not all of our Outlook 2003 users though) connecting to Exchange 2010 - anyone manage to find a solution? Would be grateful if you could post it.
Dave
FAQ по Microsoft Exchange Server » Клиенты Outlook 2003 не могут подсоединиться к Microsoft Exchange Server 2010 Says:
April 9th, 2011 at 1:33 pm
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