Description of the Expand List feature in Outlook 2003

Applies to: Microsoft Office Outlook 2003Microsoft Office Outlook 2007


When you add a distribution list (DL) to the
To, the Cc, or the Bcc boxes of your e-mail message, a plus sign (+) appears to the left of the DL name. The plus sign (named the Expand List) is a new feature in Microsoft Office Outlook 2007 and Microsoft Office Outlook 2003.

This article describes the Expand List feature and some important considerations when you use this feature.

More Information

The Expand List feature allows you to expand a DL directly in the recipient boxes (the To, the Cc, and the Bcc boxes). After you expand the DL, the recipient boxes of your e-mail message will display the resolved names of all the DL members.

If you want to send an e-mail message to everyone in a DL except for one or two people, you can expand the DL and then remove the recipients that you do not want to receive the e-mail message. The new Expand List feature makes it very easy for you to address an e-mail message to a very large number of people.

The Expand List feature uses the same technology from Microsoft Outlook 2002 that permitted the expansion of DLs in the Meeting Planner. When you expand a DL, you receive the following message:
If you expand the list, Outlook will replace the list with its members. You will not be able to collapse it again.
The Expand List dialog box contains the Please do not show me this again check box. If you click to select the Please do not show me this again check box, the information is stored in the registry.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows

The Expand List dialog box is controlled by the following registry key:

Outlook 2003


Outlook 2007

The PONT_STRING registry value is stored as a string of comma-delimited values. When the Please do not show me this again check box in the Expand List dialog box is selected, "13" is added as one of the values in PONT_STRING. To have the Expand List dialog box appear when you expand a distribution list, remove "13" from the list of values.

Note The PONT_STRING registry setting controls whether or not the Expand List warning appears. The default REG_SZ string value for the PONT_STRING value is "32,". The default value includes the comma.

Important Considerations When Use the Expand List Feature to Expand a DL

  • Most mail servers limit the maximum number of recipients that an e-mail message header may contain. If you exceed this limit, you receive a non-Delivery Receipt (NDR).
  • After you expand a DL, you cannot collapse the DL again.
  • DLs that reside across forests do not display the plus sign and are not expandable because cross forest DLs are not recognized as a DL by the client. Instead, the DL is represented by Simple Mail Transfer Protocol (SMTP) addresses in the Global Address List (GAL) that the client uses to address the cross forest DL.
  • There are no client side configuration options, limits, or throttles available for the Expand List feature.
  • Client side DL expansion cannot be turned off, but it can be regulated by the mail server Max Recipients configuration. Microsoft Exchange 2000 Server and Microsoft Exchange Server 2003 servers both set the Max Recipients value at 5000. Most consumer Internet service providers (ISP) will limit you to 10 recipients. This option can be configured in the Exchange System Manager (ESM) properties of Message Delivery (global settings).
  • Whenever a large DL is expanded, Outlook will take a performance hit as it extracts the addresses and populates the individual recipients. Performance in this case would be relative to the size of the DL and the configuration of the system that Outlook is running on.