Category Archives: 15006

Update: How to Configure Fast Cached Exchange Mode Settings for Outlook 2013 Using Group Policy


With the release of Office 2013 right around the corner and quite a number of people already running the Office 2013 Consumer Preview, I thought I’d update a previous article I wrote that speeds up Outlook performance.



How to Configure Fast Cached Exchange Mode Settings for Outlook 2010 and Outlook 2013 Using Group Policy explains how to configure Outlook 2010 and Outlook 2013’s Cached Exchange Mode send/receive behavior.  With these changes Outlook cached mode behaves very similar to online mode.  There is no change in network bandwidth with this configuration – it just configures Outlook to go on “mail runs” more frequently.

How to Fix Legacy GAL Segmentation Issues in Exchange 2010

I’m working for a customer who is migrating from Exchange 2003 to Exchange 2010.  The customer used “old school” GAL segmentation to create different address lists and Default Global Address Lists (GALs) for some users.  Prior to Exchange 2010 SP2, this was done by configuring ACL permissions on Address Lists using ADSI Edit.  Not only was this fairly complex, it was also not officially supported by Microsoft.  There was still a genuine business need for GAL segmentation and a number of companies did it anyway.



Exchange 2010 SP2 introduces GAL segmentation using Address Book Policies (Thanks, Greg Taylor!)  This is the only GAL segmentation that is supported by Microsoft.  The trouble is that only Exchange 2010 mailboxes can benefit from this form of segmentation.  If you’re doing a migration from a previous version to 2010, the legacy mailbox users won’t see it.  In the case of my customer, that means ripping out all the legacy ACLs first and configuring Address Book Policies later.



I ran into some strange issues when I reset the ACL permissions, so I want to explain what I did and how I did it to overcome these issues.



The organization had a very elaborate set of permissions on their address lists.  They had 8 separate All Users address lists and 5 separate Default Global Address Lists.  With many child domains, it made it difficult to determine which permissions were applied and which were inherited at all the different levels.  I decided to use ADSI Edit to delete all the address lists and GALs and recreate them on the Exchange 2003 side.  Here’s how I did this:



  • Open ADSI Edit and navigate to CN=All Address Lists,CN=Address Lists Container,CN=[OrgName],CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=[domain],DC=[com]
  • Delete all the address lists in this container except All Rooms (All Contacts, All Groups, All Users, etc.).  All Rooms is an Exchange 2010 address list and will not need to be recreated.



  •  Navigate to CN=All Global Address Lists,CN=Address Lists Container,CN=[OrgName],CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=[domain],DC=[com]
  • Delete all the Global Address Lists including the Default Global Address List

Now recreate the address lists and Default Global Address List in Exchange 2003.  I did it this way to ensure that current 2003 mailboxes can use the new lists.



Once the address lists have been created and replicated throughout the domain, you can upgrade them to Exchange 2010 versions using OPath and you should be good to go.



However, if your organization used ACLs for Exchange 2003 GAL segmentation there’s a very good chance that OWA was segmented, as well.  OWA GAL segmentation is done an entirely different way, and if you don’t undo these changes Exchange 2010 users will not see the Default Global Address List or the All * lists in Outlook.



OWA GAL segmentation is done by configuring the msExchangeQueryBaseDN attribute on the user object in AD.  Normally this attribute is empty (Null).  For GAL segmentation in OWA, the msExchangeQueryBaseDN attribute is set to the distinguishedName of the OU where you want the GAL scoped to.






Simply clear the msExchangeQueryBaseDN value for the user, wait for it to replicate and the address lists will show up for online (non-cached mode) users.  The user doesn’t even need to close Outlook.



Cached mode users will need to download the new OAB to see the address lists.  This will happen automatically within 24 hours, or the user can download the OAB manually in Outlook.  You’ll need to either let the OAB update automatically at 4am or update it manually with the Update-GlobalAddressList cmdlet first.



 Here’s an EMS one-liner that will clear the msExchangeQueryBaseDN for all users in the organization:

Get-Mailbox | Foreach{ $dn = “LDAP://” + $_.distinguishedname;$obj = [ADSI]$dn;$obj.msExchQueryBaseDN.Clear();$obj.SetInfo()}

How to Configure Fast Cached Exchange Mode Settings for Outlook 2010 Using Group Policy

Microsoft introduced Cached Exchange Mode in Outlook 2003, and it’s been the default configuration ever since.  Cached Exchange Mode saves a copy of your mailbox on your computer which provides quick access to your data and is frequently updated with the Exchange server.


Cached Exchange Mode works like this: When the Exchange Server notifies Outlook of a change, the Download timer starts and Outlook delays receiving the change information.  All notifications that occur in the 30 second window of the Download timer are grouped and processed as a batch at the end of the timer.  The timer is then reset.  Uploads to Exchange use a similar Upload timer, which lasts 15 seconds.  For more information, see Description of Outlook 2003 with Cached Exchange Mode in an Exchange Server 2003 environment.  This behavior is the same in Outlook 2007 and Outlook 2010.

While this configuration reduces network utilization and load on the target Exchange servers, it reduces the “perceived” performance of Outlook/Exchange.  Users who change from Online Mode to Cached Exchange Mode frequently complain about slow performance, since they’re used to the almost “instant messaging” behavior of Online Mode.

This behavior can be changed using a simple registry change, or, as I recommend, using Group Policy.  By changing the Download, Upload, and Maximum timers to one second, your users will enjoy much improved email performance and you will still see improved network performance over traditional MAPI “Online Mode”.

 Install the Fast Exchange Cached Mode GPO Administrative Template:
  • Download the CachedMode.adm Group Policy administrative template and save it to a temporary folder.
  • Open the Group Policy Management Console.
  • Navigate to the Default Domain Policy, right-click it, and choose Edit.
  • Navigate to User Configuration > Policies > Administrative Templates.
  • Right-click Administrative Templates and select Add/Remove Templates.
  • Click Add and browse to the location where you downloaded the CachedMode.adm template.  Click OK.
  • The Outlook 2010 Cached Mode Settings administrative template will be added under the heading “Classic Administrative Templates (ADM)“.
  • Edit the Outlook 2010 Cached Mode Settings policy and Enable each of the three policies.
  • Close the Group Policy Management Console.
The Outlook users will need to download the new policy and either restart their computer or restart Outlook to get the new settings.

If you are a VPN user or a mobile user who cannot receive Group Policy settings, you can download the FastCachedMode.reg file, and install it manually.  Then close and re-open Outlook to get the new configuration.