Downgrading Outlook and backwards compatibility

There can be various reasons which will require you to downgrade to a previous version of Outlook such as the current trial/beta version expiring or compatibility issues with some needed add-ins or business software. This guide provides solutions to various problems you may encounter when trying to downgrade Outlook or when you need to remain compatible with previous versions of Outlook.

Uninstall Office or just Outlook

As only one version of Outlook can exist on a system, you must first remove your current version of Outlook before attempting to install a previous version. If Outlook is part of an Office Suite, it is recommended to uninstall the entire Office Suite.

Uninstalling Office or Outlook will not delete any of your Outlook data such as emails, contacts or appointments; it does not even remove your account configuration settings. Still, it is always a good practice to have a recent backup of your data.
For backup instructions for Outlook see; Backup and Restore.

Uninstalling Outlook/Office can be done via the Control Panel in Windows. In Windows XP you'll find an item there called "Add/Remove Programs". In Windows 7 and Windows Vista you can do this via "Uninstall a program". Another way to uninstall Office is to insert your Office CD/DVD, start the Installer and choose "Remove".

If the uninstall process fails or if Microsoft Office is not listed at all in your list of installed applications, then you can use the automated "Fix It" solution for your version of Office.

When you use the "Add or Remove Features" option of the installer, you can choose to only uninstall Outlook instead of your entire Office Suite. If you choose to go this route, once you've installed a previous version of Outlook, you must run a Repair installation on your current version of Office again. This is because having multiple versions of Office is only supported when you install it in version order from oldest to newest. By doing a repair installation on for later versions of Office which were already installed, you'll achieve the same effect.

If you have additional Office applications installed belonging to a later version but which are not part of your installed Office Suite (such as Visio or Project), you must also do a repair on these applications after installing a previous version of Outlook.

Backward compatibility of the Mail Profile

When downgrading from a previous version of Outlook, it is highly recommended to recreate your mail profile. While you may not notice any issues at first, you might run into "strange" issues later on. The process of recreating your mail profile is described here; Recreating your mail profile.

When you downgrade from Outlook 2010 and then start using Outlook 2007 again, you'll actually be presented with an error that the mail profile was created with a newer version of Outlook and that the mail profile needs to be recreated. While you can dismiss this error/warning in most cases and continue to work in Outlook without problems, it is of course not recommended.

This warning will show each time when you start Outlook. If you want to get rid of this error but do not want to recreate your mail profile, you can do this by modifying the Registry;

Key: HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles\<profile name>\0a0d020000000000c000000000000046
Value name: 0003036f
Value type: REG_BINARY

Right click on 0003036f and choose Delete. Now when you start Outlook, the warning message will be gone and Outlook will automatically recreate the key with the correct value for the current version.

The mail profile "Outlook" was created with a newer version of Outlook and might contain information that is not compatible with your current Outlook version. If you experience problems with this profile, you can create a new profile. In Windows Control Panel, open Mail, then click Show Profiles, and then click Add.
While not advised, you can get rid of this error without recreating your mail profile by editing the registry. (click on image to enlarge)

You must replace <profile name> with the name of your mail profile. By default this is called "Outlook". If your mail profile is also called "Outlook" then you can use the registry key in this download and execute it to make the modifications for you without needing to go into the registry yourself.

Downgrading from the Click2Run version of Office 2010

If you were using the Click2Run version of Office 2010, then no changes would have been made to the current installation of Office or Outlook; any previously installed version is still there and accessible.

When the Click2Run version of Outlook got started for the first time, it made a copy of any existing settings and mail profiles. This means that there is no need to recreate your mail profile since no modifications have been made to your existing settings.

While the Click2Run version did not affect your settings, it did however used any configured existing pst-file to store your data in. This is no problem at all and it means there is no need to get your data out of Outlook 2010 in order to make it available in your other installed Outlook version.

Backwards compatibility of the pst-file

If you are currently using Outlook 2003 or newer and want to continue or need to be compatible with Outlook 2002/XP or previous, you'll have to convert your pst-file to the ANSI format before uninstalling Outlook 2003 or newer. This is because Outlook 2003 and newer use a new Unicode format of the pst-file which Outlook 2002/XP and previous cannot read.

Any-files that you have created in Outlook 2010 can also be used in Outlook 2003 and Outlook 2007.

If you have already uninstalled Outlook 2003 or later and need to convert your pst-file from the Unicode format to the ANSI format, you can use the Click to Run trial version of Office 2010 Home and Business or Professional. The Click to Run version of Office 2010 will allow you to use Office 2010 without actually installing anything on your system or otherwise affecting your current Office installation.

Step 1: Create a new Outlook 97-2002 Data File

  1. Create a new Outlook 97-2002 Data File by using
    • Outlook 2003 and Outlook 2007
      File-> New-> Outlook Data File…
      In the New Outlook Data File prompt screen select Outlook 97-2002 Personal Folders File (.pst) and press OK
    • Outlook 2010
      On the Home tab click;
      New Items-> More Items-> Outlook Data File…
      Expand the “Save as type” list to show the option;
      Outlook 97-2002 Data File (.pst)
  2. Browse for the location where you want to create the new Data File and press OK
  3. If you want you can now set extra properties for the Data File and press OK
  4. The new Data File will show up in your Folder List now

Step 2: Copying the data to the Outlook 97-2002 Data File

You can do this in several ways.

Option 1

  1. Right click on the folder you want to copy and choose Copy Folder.
  2. In the dialog that pops-up, select the folder top folder of the Outlook 97-2002 Data File and press OK.
  3. Repeat this for every folder you want to copy.

Remember that the file size of an Outlook 97-2002 Data File can’t exceed 2GB. Therefore when your current Data File is bigger than 2GB, you’ll need to create several Outlook 97-2002 Data Files to copy your data to.

Option 2

  1. Open the Import and Export wizard
    • Outlook 2003 and Outlook 2007
      File-> Import and Export…
    • Outlook 2010
      File-> Open-> Import
      (the actual Export option in Outlook 2010 can be found in File-> Options-> section Advanced-> button Export… but it will launch the same dialog as the above mentioned shorter path)
  2. Choose Export to a file and press Next.
  3. Choose Personal Folder File (.pst) and press Next
  4. Choose the folder you want to export. In case you want to export the complete Data File, select Outlook Today and select the option "Include Subfolders" and press Next
  5. Browse to the location where you saved the pst-file created in step 1 and press Finish

The newly created pst-file can now be opened in any version of Outlook.

Solving issues when starting a downgraded Outlook version

If you are running into issues after you have downgraded your Outlook version even after recreating your mail profile, regular troubleshooting steps apply as described in; Outlook doesn't start.

The main troubleshooting areas to focus on are;

  • Making sure that you have updated Outlook with the latest Service Packs and additional updates.
  • Resetting your dat-files.
  • Checking or reinstalling your add-ins.