Last reviewed on January 25, 2015   —  32 Comments

To avoid releasing potentially private information on outgoing email messages, categories are not sent with email in Outlook 2003 and up when you use Exchange server mailboxes. When you use categories with internal codes or potentially embarrassing keywords, the recipient will not see them.

This does not apply to POP3 or IMAP accounts. The Category is removed by Exchange Server’s transport rules, not Outlook, when the message is sent. A rule in Outlook 2007 and 2010 removes categories as messages are downloaded; Outlook 2013 does not have this rule, users will need to create the rule to remove categories.

If you need to send categories on outgoing email you can use the SendPersonalCategories registry entry.

Warning: when making this change, the categories will be included on the sent message and the recipient will be able to see the category (unless the recipient uses a rule to remove categories from messages they receive).

Create the key or path if it does not exist. This key should take effect without restarting Outlook.

In Outlook 2013 RTM, the SendPersonalCategories key does not work. The Category is kept on Sent Items in your mailbox only. It’s fixed in a later update.

Outlook 2013

DWORD: SendPersonalCategories
Value Data: 1 to keep categories on sent mail, 0 to not include categories

Outlook 2010

DWORD: SendPersonalCategories
Value Data: 1 to keep categories on sent mail, 0 to not include categories

Outlook 2007

DWORD: SendPersonalCategories
Value Data: 1 to keep categories on sent mail, 0 to not include categories

Outlook 2003

DWORD: SendPersonalCategories
Value Data: 1 to keep categories on sent mail, 0 to not include categories

If you setting the SendPersonalCategories value, users can still delete the categories as messages arrive by using a rule.

Do it for me

If you don’t want to edit the registry yourself, you can download and run a registry file to make the changes. This reg file also sets AcceptCategories value.

Outlook 2013Outlook 2010Outlook 20072003

Default Rule to Remove Categories

Outlook 2007 and up have a default rule that removes categories from messages as they arrive. Delete the rule or disable it if you want to keep the categories.

Outlook's default rule to remove categories

Remove Categories using a Macro

If categories are being sent, you can use a macro to remove the categories as the message is sent. Place the macro into ThisOutlookSession.

Private Sub Application_ItemSend(ByVal Item As Object, Cancel As Boolean)
Item.Categories = ""
End Sub

Exchange rule to remove categories

In Exchange 2007 and up, categories are removed from messages. To disable it, the administrator can use this cmdlet to change the transport setting.

Set-transportconfig -clearcategories $false

Other methods

If you need to include the category on a one time basis, drag the item to the hard drive, zip it and email the zip file. The recipient will drag the item to a folder in their Outlook and if using Outlook 2007, can add the categories to their master list by using the Upgrade to color categories option in the root folder properties.

Add Categories to Master list

In Outlook 2007 or 2010, to add a category that is not in your master list, to your master list, select it (so its highlighted) and click the New button.

Not in master list

Outlook will assign the next unused color – change the color and set a shortcut key, if desired, then click Save.

Adding Categories when Composing Email

The Categories button is not available when you are composing new messages. When you need to assign categories, you need to add the category to the message either in the Sent folder or in the Outbox.

To add the category before hitting Send, you can use VBA to open the Categories dialog. Add the following code to the VB Editor and then add a button to the QAT, Ribbon, or Toolbar of a message form. Click the button to open the Category dialog.

'by Michael Bauer
Public Sub ShowCategoriesDialog()
  Dim Mail As Object
  Set Mail = Application.ActiveInspector.CurrentItem
End Sub

More Information

Outlook Categories (Slipstick)
More Category VBA Code Samples by Michael Bauer:
E-Mail: Categorizer for outgoing e-mails
E-Mail: Categorize and move


  1. Rick Medford (@rickmedford) says

    Any idea how to stop Outlook 2013 from stripping the categories on outgoing mail?

    • Diane Poremsky says

      Did you try the key? It should work on 2013 too. Okay, so it looks like the key does not work. I'll check on it because it is the only way to keep categories, short of sending messages in an attached zip file.

    • Diane Poremsky says

      Are you using Exchange server? The server may be stripping them - once I remembered the default is to strip categories, I ran the cmdlet to keep categories and the key works in 2013. If neither the sending nor receiving system in Exchange, categories *should* stick with that key set.

      Set-transportconfig -clearcategories $false

  2. jacopo3001 says

    I am in an Exchange environment, configured by IT.
    When I send emails, my recipients get to see my categories!

    How can I avoid this? I don't want my colleague to see my way of organizing emails

    • Diane Poremsky says

      Check the registry at HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\xx.0\Outlook\Preferences (xx = your version of Outlook) for a key named SendPersonalCategories. It should either not exist or be set to 0. If it exists and is set to 1, speak to your Exchange admin and ask them to change it.

  3. Ian Slater says

    When the mail is answered will the categories still exist in my inbox? Or are they dependent on the recipients set up?

    • Diane Poremsky says

      it's dependent on the recipients set up. however, if you use outlook 2010/2013 with conversations enabled, you should see the category of your original message and can add it to the reply.

    • Diane Poremsky says

      BTW, what is your build number? I'll check in both older builds and SP1. The moderator in that forum post is probably using SP1.

  4. Alex K says

    First line of the About window:
    Microsoft Outlook 2013 (15.0.4551.1511) MSO (15.0.4551.1508) 64-bit.

    I really appreciate you looking into this, Diane.

    • Diane Poremsky says

      Thanks. That is the last pre-SP1 build. I'm assuming you are using a subscription version so it won't be updated for about 2 weeks (assuming i can repro the bug in that build and not in SP1.)

    • Diane Poremsky says

      I haven't had a chance to test it yet - I do have the key set and can send categories. Make sure you check for the key, both in the regular location and also in HKEY_CURRENT_USER\Software\Policies\Microsoft\office\15.0\outlook\preferences - I recommend deleting it, rather than changing it to 0.

    • Diane Poremsky says

      Actually, after sleeping on it... I think the bug is that Outlook 2013 doesn't create the 'delete categories' rule for incoming mail, which it does in 2003, 2007 and 2010. This removes the categories. Exchange server also removes the categories - at the transport level - but Outlook doesn't have the capability to remove categories from mail as its being sent and leave it on the message. Without the rule (and to insure recipients can't see the category) you need to use an addin or a macro to categorize sent messages.

  5. Alex K says

    Having a rule to strip categories on incoming messages does not protect from information leak :(

    And judging from what the page you linked says, the leak is actually "by design". "Be very careful about categorizing your outgoing messages — your recipients might be able to see your categories". This is unfortunate.

    Diane, thank you so much for getting to the bottom of it! At least now it is clear that Outlook is not stripping categories which as assigned before a message is sent, unless sender is using Exchange.

    • Diane Poremsky says

      No, it doesn't prevent PII leakage. The mvps discussed it this morning and had some of the same confusion we had last night. I don't know if some of the information was lost when the site was moved into the wordpress but I'll make it more clean since more people will notice this problem since the rule is no longer added by default - that hid the problem from many users.

  6. Cameron Robinson says

    I cannot seem to get this to work for Outlook in Office 365 using the Office 365 Email server. HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\15.0\Outlook\Preferences does not exist. Only HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\15.0\Outlook\Security

    • Diane Poremsky says

      if a key doesn't exist, you need to create it. right click on the Outlook key and choose New>

    • Diane Poremsky says

      Did you restart Outlook? What version of Outlook do you use? Did you type the key in or use the reg files I included?

  7. Cam Robinson says

    Yes, I restarted Outlook. I am using Office 365 which I believe is the latest version of Outlook. I did it twice. First manually and then with the reg files.

    • Diane Poremsky says

      Offhand, I don't know why its not working for you. It should (and does here). Sorry.

  8. G says

    Somehow I got one computer to work perfectly fine but the rest I cannot get to work and here are the steps I've taken:

    Added these regedits:


    Also went into the powershell msonline and changed the transportconfig clearcategories to false.

    What else could be making outlook strip categories from meeting invites before sending them?

    In OWA, I can send categories in my invites perfectly between all users so this is definitely 100% an outlook issue.

    • Diane PoremskyDiane Poremsky says

      Are their any rules that are removing categories? They are usually set on the recipients end though.

      Did you export the reg keys from the working computer and run it on the others? This will eliminate spelling errors.

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