Internet Explorer Client Registry Layout

Microsoft® Internet Explorer supports user selection of Internet service applications, such as mail and news clients. This article describes how to make your Internet service applications available to Internet Explorer. The registry settings referred to in this article are supported in Internet Explorer version 4.0 and later, unless otherwise indicated.

Programmatic access to the registry is beyond the scope of this article. For more information on the registry in Microsoft® Windows® 95 and later, see the Microsoft Platform Software Development Kit (SDK).

File Menu Items

Internet Explorer provides File menu commands that allow users to launch another instance of Internet Explorer or to select Internet services that are not included as part of Internet Explorer. The Internet Explorer File menu offers users the ability to start a new Internet service—such as e-mail, news, an Internet conference, or an address book database—and to send a link or page as e-mail to another Internet address.

The Edit command on the File menu in Internet Explorer 5 and later enables users to edit Web pages using the HTML editor they choose as their default.

View Menu Items

Internet Explorer provides the View Source command, which enables users to view the HTML source file for the current page. The View Source command is also available from the Web page's context menu. With Internet Explorer 5 and later, users may select editors other than Notepad for viewing source code.

Currently, this feature works with programs that permit spaces in the command path. WordPad, for example, does not permit spaces in the command path, so you cannot specify WordPad as your default editor for viewing source code.

Toolbar Buttons

HTML editors can also be launched from the toolbar by clicking the Edit button. Internet Explorer 4.0 launches Microsoft FrontPage® or FrontPage Express, if installed, when the Edit button is pressed. The Edit button on the toolbar in Internet Explorer 5 and later also enables users to edit Web pages using their chosen HTML editor.

Internet Options

Internet Explorer provides the ability for the user to select which application will be launched when accessing its corresponding Internet service, such as mail or news. Internet Explorer will launch and use applications defined in the registry as default client applications. Client applications are listed within a corresponding drop-down menu that relates to the client application type.

Internet Explorer 5 and later also allows the user to select a default HTML editor. Registered HTML editors that the user may choose from are listed in a drop-down menu on the Programs tab of the Internet Options dialog box.

How to Modify the Registry

This section describes how to add your application to the list of Internet service applications available to Internet Explorer.

By changing the values that are stored in the registry for extended services such as mail and news, it is possible for Internet Explorer to launch applications that provide specialized Internet services. By appending new key definitions to the end of the registry path, it is possible to add other applications to the menu items that are available within Internet Explorer.

Warning Internet Explorer does not provide user interface functionality for users to directly interact with the registry; therefore, it is not recommended that users be encouraged to make modifications to the registry settings. For additional information on the Windows 95 registry, see the Microsoft Platform Software Development Kit (SDK).

Adding Client Applications

For example, to include a mail client application in the list of available applications, follow these steps:

HKLM\SOFTWARE\Clients\Mail\Your_Mail_Client_Name

Define the client and the path to the application to be launched by Internet Explorer.

HKLM\SOFTWARE\Clients\Mail\Your_Mail_Client_Name
\shell\open\command\"C:\Program Files\
Your Directory Name\YOUR_MAIL_CLIENT_NAME.EXE"

Once the registry is modified to include the new mail client application, Internet Explorer adds Your_Mail_Client_Name to the drop-down list of available e-mail applications. From this list, users can specify the mail client they want to be their default e-mail application. When the user selects the New Message item from the File menu, or one of the items available from the Mail toolbar button, Internet Explorer launches the application the user specified as the default e-mail application.

Adding HTML Editors

The steps for adding HTML editors to the drop-down list on the Programs tab of the Internet Options dialog box in Internet Explorer 5 and later are slightly different than the steps for adding client applications like mail and news.

Register the friendly name of the HTML editor by adding a new key to HKEY_CLASSSES_ROOT\.htm\OpenWithList.
```
HKEY_CLASSES_ROOT\.htm\OpenWithList\friendly name
```

Add shell, edit, and command keys to the editor's registry entry.

HKEY_CLASSES_ROOT\.htm\OpenWithList\friendly name\shell\edit\command

Enter the fully formed path of the .exe file that launches the editor in the command key's "Value data" field. Enclose the path in quotes if it contains spaces. The following example shows the Value data entry for a typical installation of FrontPage Express. Include %1 as a parameter. This parameter refers to the file name of the active Web page.
```
"c:\program files\microsoft front page express\bin\fpxpress.exe %1"
```

Registry Overview

This section outlines the registry settings used by Internet Explorer to determine which clients to use and how to use them. The section also outlines the registry settings that third-party clients must provide to be recognized and used by the system as the default client.

In Microsoft® Windows® 95/98, Windows NT® 4.0, and Windows® 2000 and later, the system registry contains the settings used by Internet Explorer to access the client services of other applications from within Internet Explorer. Internet Explorer establishes the default settings for these menu items during the installation process. These default settings are stored within the registry database as defined in the following section>.

Client Registry Key Definitions

This section defines the registry keys for Internet service applications used by Internet Explorer.

The Calendar, Contacts, Internet Call, Mail, and News registry settings can be found under the SOFTWARE\Clients subkey of HKEY_LOCAL_MACHINE. The HTML editors registry settings can be found under the SOFTWARE\Microsoft\Internet Explorer\Default HTML Editor subkey of HKEY_CLASSES_ROOT.

Note For the purpose of this discussion, the registry key HKEY_LOCAL_MACHINE is abbreviated as HKLM.

When Internet Explorer is installed, the default value for the Mail subkey is Outlook Express; thus, further configuration information about this client can be found at HKLM\SOFTWARE\Clients\Outlook Express.

Client Registry Keys

Registry keys for Calendar clients

Key Value

HKLM\SOFTWARE\Clients\Calendar (default)

Specifies the subkey name where information about the default calendar client can be found.

HKLM\SOFTWARE\Clients\Calendar\clientname\shell\open\command (default)

Contains the command line that will launch the Calendar client into its default view.

Registry keys for Contacts clients

Key Value

HKLM\SOFTWARE\Clients\Contacts (default)

Specifies the name of the subkey where information about the default Contacts client can be found.
The root key of the information for the Contacts client can be found by appending this string to HKLM\Software\Clients\Contacts.

HKLM\SOFTWARE\Clients\Contacts\clientname (various)

Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\ldap in order to service lightweight directory access protocol (LDAP) URLs.
This entire registry hierarchy replaces the existing LDAP: registry hierarchy.

HKLM\SOFTWARE\Clients\Contacts\clientname\shell\open\command (default)

Contains the command line that will launch the Contacts client into its default view.

Registry keys for HTML editors

Key Value

HKEY_CLASSES_ROOT\.htm\OpenWithList\<friendly name>\shell\edit\command (various)

Contains the command line path for the .exe file that launches the .htm editor and opens the .htm file.

HKEY_CLASSES_ROOT\.html\OpenWithList\<friendly name>\shell\edit\command (various)

Contains the command line path for the .exe file that launches the .html editor and opens the .html file.

Registry keys for Internet Call clients

Key Value

HKLM\SOFTWARE\Clients\Internet Call (default)

Specifies the name of the subkey where information about the default Internet Call client can be found.
The root key of the information for this client can be found by appending this string to HKLM\Software\Clients\Internet Call.

HKLM\SOFTWARE\Clients\Internet Call\Microsoft NetMeeting (default)

Specifies the friendly name for the Internet call client.
The list of clients in the Internet Options dialog box is generated by enumerating all the client subkeys and appending the friendly name for each to the list.

HKLM\SOFTWARE\Clients\Internet Call\Microsoft NetMeeting\Protocols\callto (various)

Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\callto to service URLs that use the callto protocol.
This entire registry hierarchy replaces the existing callto: registry hierarchy.

HKLM\SOFTWARE\Clients\Internet Call\Microsoft NetMeeting\Protocols\callto\shell\open\command (default)

Contains the command line that will launch the Internet Call client into its default view.

Registry keys for Mail clients

Key Value

HKLM\SOFTWARE\Clients\Mail (default)

Specifies the name of the subkey where information about the default mail client can be found.
The root key of the information for this client can be found by appending this string to HKLM\Software\Clients\Mail.

HKLM\SOFTWARE\Clients\Mail\clientname (default)

Specifies the friendly name for this client.
The list of clients in the Internet Options dialog box is generated by enumerating all the client subkeys and appending the friendly name for each to the list.

HKLM\SOFTWARE\Clients\Mail\clientname DLLPath

Contains the path to the .dll or .exe file to be used for simple MAPI calls. If this key is present and the mail client is the default, this .dll/.exe will be used. If the key is not present, the .dll/.exe associated with the CMCDLLName32 name/value pair in the [Mail] section of the Win.ini file will be used. If the Win.ini entry is not present, Mapi32.dll will be used. In Internet Explorer, the following menus use simple MAPI calls:

File/New/Message
File/Send/Page By E-mail
File/Send/Link By E-mail

HKLM\SOFTWARE\Clients\Mail\clientname\Protocols\mailto (various)

Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\mailto to service URLs that use the mailto protocol.
This entire registry hierarchy replaces the existing mailto: registry hierarchy.

HKLM\SOFTWARE\Clients\Mail\clientname\shell\open\command (default)

Contains the command line that will launch the mail client into its default view (typically the Inbox).

Registry keys for News clients

Key Value

HKLM\SOFTWARE\Clients\News (default)

Specifies the name of the subkey where information about the default news client an be found.
The root key of the information for this client can be found by appending this string to HKLM\Software\Clients\News.

HKLM\SOFTWARE\Clients\News\clientname (default)

Specifies the friendly name for this client.
The list of clients in the Internet Options dialog box is generated by enumerating all the client subkeys and appending the friendly name for each to the list.

HKLM\SOFTWARE\Clients\News\clientname\Protocols\news (various)

Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\news to service news URLs.
This entire registry hierarchy replaces the existing news: registry hierarchy.

HKLM\SOFTWARE\Clients\News\clientname\Protocols\nntp (various)

Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\nntp to service URLs that use the NNTP protocol.
This entire registry hierarchy replaces the existing NNTP: registry hierarchy.

HKLM\SOFTWARE\Clients\News\clientname\Protocols\snews (various)

Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\snews to service URLs that use the snews protocol.
This entire registry hierarchy replaces the existing snews: registry hierarchy.

HKLM\SOFTWARE\Clients\News\clientname\shell\open\command (default)

Contains the command line that will launch the news client into its default view.

View source editors

Key Value

HKLM\SOFTWARE\Microsoft\Internet Explorer\View Source Editor\Editor Name (default)

Contains the command line path for the .exe file that launches the editor for viewing source code.

Registry keys for Calendar clients
Key	Value
HKLM\SOFTWARE\Clients\Calendar	(default)
Specifies the subkey name where information about the default calendar client can be found.
HKLM\SOFTWARE\Clients\Calendar\clientname\shell\open\command	(default)
Contains the command line that will launch the Calendar client into its default view.
Registry keys for Contacts clients
Key	Value
HKLM\SOFTWARE\Clients\Contacts	(default)
Specifies the name of the subkey where information about the default Contacts client can be found. The root key of the information for the Contacts client can be found by appending this string to HKLM\Software\Clients\Contacts.
HKLM\SOFTWARE\Clients\Contacts\clientname	(various)
Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\ldap in order to service lightweight directory access protocol (LDAP) URLs. This entire registry hierarchy replaces the existing LDAP: registry hierarchy.
HKLM\SOFTWARE\Clients\Contacts\clientname\shell\open\command	(default)
Contains the command line that will launch the Contacts client into its default view.
Registry keys for HTML editors
Key	Value
HKEY_CLASSES_ROOT\.htm\OpenWithList\<friendly name>\shell\edit\command	(various)
Contains the command line path for the .exe file that launches the .htm editor and opens the .htm file.
HKEY_CLASSES_ROOT\.html\OpenWithList\<friendly name>\shell\edit\command	(various)
Contains the command line path for the .exe file that launches the .html editor and opens the .html file.
Registry keys for Internet Call clients
Key	Value
HKLM\SOFTWARE\Clients\Internet Call	(default)
Specifies the name of the subkey where information about the default Internet Call client can be found. The root key of the information for this client can be found by appending this string to HKLM\Software\Clients\Internet Call.
HKLM\SOFTWARE\Clients\Internet Call\Microsoft NetMeeting	(default)
Specifies the friendly name for the Internet call client. The list of clients in the Internet Options dialog box is generated by enumerating all the client subkeys and appending the friendly name for each to the list.
HKLM\SOFTWARE\Clients\Internet Call\Microsoft NetMeeting\Protocols\callto	(various)
Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\callto to service URLs that use the callto protocol. This entire registry hierarchy replaces the existing callto: registry hierarchy.
HKLM\SOFTWARE\Clients\Internet Call\Microsoft NetMeeting\Protocols\callto\shell\open\command	(default)
Contains the command line that will launch the Internet Call client into its default view.
Registry keys for Mail clients
Key	Value
HKLM\SOFTWARE\Clients\Mail	(default)
Specifies the name of the subkey where information about the default mail client can be found. The root key of the information for this client can be found by appending this string to HKLM\Software\Clients\Mail.
HKLM\SOFTWARE\Clients\Mail\clientname	(default)
Specifies the friendly name for this client. The list of clients in the Internet Options dialog box is generated by enumerating all the client subkeys and appending the friendly name for each to the list.
HKLM\SOFTWARE\Clients\Mail\clientname	DLLPath
Contains the path to the .dll or .exe file to be used for simple MAPI calls. If this key is present and the mail client is the default, this .dll/.exe will be used. If the key is not present, the .dll/.exe associated with the CMCDLLName32 name/value pair in the [Mail] section of the Win.ini file will be used. If the Win.ini entry is not present, Mapi32.dll will be used. In Internet Explorer, the following menus use simple MAPI calls: File/New/Message File/Send/Page By E-mail File/Send/Link By E-mail
HKLM\SOFTWARE\Clients\Mail\clientname\Protocols\mailto	(various)
Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\mailto to service URLs that use the mailto protocol. This entire registry hierarchy replaces the existing mailto: registry hierarchy.
HKLM\SOFTWARE\Clients\Mail\clientname\shell\open\command	(default)
Contains the command line that will launch the mail client into its default view (typically the Inbox).
Registry keys for News clients
Key	Value
HKLM\SOFTWARE\Clients\News	(default)
Specifies the name of the subkey where information about the default news client an be found. The root key of the information for this client can be found by appending this string to HKLM\Software\Clients\News.
HKLM\SOFTWARE\Clients\News\clientname	(default)
Specifies the friendly name for this client. The list of clients in the Internet Options dialog box is generated by enumerating all the client subkeys and appending the friendly name for each to the list.
HKLM\SOFTWARE\Clients\News\clientname\Protocols\news	(various)
Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\news to service news URLs. This entire registry hierarchy replaces the existing news: registry hierarchy.
HKLM\SOFTWARE\Clients\News\clientname\Protocols\nntp	(various)
Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\nntp to service URLs that use the NNTP protocol. This entire registry hierarchy replaces the existing NNTP: registry hierarchy.
HKLM\SOFTWARE\Clients\News\clientname\Protocols\snews	(various)
Contains a mirror of the registry settings that the application needs to have written under HKEY_CLASSES_ROOT\snews to service URLs that use the snews protocol. This entire registry hierarchy replaces the existing snews: registry hierarchy.
HKLM\SOFTWARE\Clients\News\clientname\shell\open\command	(default)
Contains the command line that will launch the news client into its default view.
View source editors
Key	Value
HKLM\SOFTWARE\Microsoft\Internet Explorer\View Source Editor\Editor Name	(default)
Contains the command line path for the .exe file that launches the editor for viewing source code.