Overview of Outlook Express

Outlook Express is a standards-based Internet messaging application integrated with the Microsoft Internet Explorer browsing software. Outlook Express contains services to read and send e-mail messages, browse and post within newsgroups, sort and store messages on the local drive or e-mail server (for Internet Message Access Protocol [IMAP] servers), and create and edit contacts in the Address Book.

Outlook Express Features

Built on Internet standards, including POP3, SMTP, IMAP4, LDAP, S/MIME, MHTML, and NNTP, Outlook Express offers a set of versatile features that are easy to use.

HTML support.

This feature allows users to send and receive messages in Hypertext Markup Language (HTML) format. HTML messages can incorporate graphics, hyperlinks, and multimedia files. Also, with its support for the Multipurpose Internet Mail Extensions (MIME) HTML (MHTML) standard, Outlook Express allows users to embed images in their messages so recipients do not need to be connected to the Internet or intranet to view the embedded images.

Multiple accounts.

Users of Outlook Express can easily maintain multiple e-mail and news accounts. When checking for new e-mail, users can specify to check all accounts or just a specific one. Likewise, when composing a message, there is a choice of which account to send the message from.

Stationery.

This unique feature of Outlook Express allows you to personalize your e-mail and news messages. Outlook Express stationery makes it easy to create messages with personalized background images, graphics, and fonts. In addition, for special occasions like birthdays or anniversaries, Outlook Express includes a variety of stationery designs from Microsoft Greetings Workshop and Hallmark. You can also download additional stationery from the Microsoft Greetings Workshop Web page.

Safe and secure e-mail.

Outlook Express uses the Internet Explorer browsing software security zones for HTML messages. The security zones feature of Internet Explorer allows you to control whether scripts and active content can be run in messages you receive.

For more information about the Internet Explorer browsing software security zones, see Chapter 20, "Internet Access and Tools." For more information about Outlook Express, see the Outlook Express Web site at http://www.microsoft.com /ie/ie40/oe/.

Outlook Express also supports Secure/Multipurpose Internet Mail Extensions (S/MIME), which allows you to digitally sign and encrypt your messages with digital certificates. Using digital signing and encryption, you can verify the source and integrity of any messages you receive, and protect messages from being read by anyone other than the intended recipients.

Outlook Express Architecture

Table 22.1 shows the main files used for Outlook Express.

Table 22.1 Outlook Express main files

File name	Definition

Inetcomm.dll	Parses MIME information and communicates with mail servers.
Msimnimp.dll	Internet Mail and News setting importer/exporter.
Msimnui.dll	Dialog boxes and other e-mail and news functions comprising most of the user interface.
Msoeacct.dll	Account manager DLL file.
Msoemapi.dll	Provides Simple MAPI support in Outlook Express.
Msoert.dll	Run-time utility functions.
Wab32.dll	Windows Address Book (WAB) core functionality.
Wabfind.dll	WAB search user interface.
Wabimp.dll	WAB import back end.
Wldap32.dll	Lightweight Directory Access Protocol (LDAP) support file for WAB and LDAP searches.
Msimn.exe	Outlook Express main program; loads Msimnui.dll.
Wab.exe	Windows Address Book; uses Wab32.dll.
Wabmig.exe	WAB import user interface.

Outlook Express Directories

When Outlook Express downloads e-mail messages and news articles, it stores them on the local hard disk. Unless you specify a different location when you first start Outlook Express, it will use the default. The path for the default location varies slightly depending on whether the User Profiles feature is turned on or not. For more information about user profiles, see Chapter 7, "User Profiles."

Without User Profiles:

Windows\Application Data\Microsoft\Outlook Express

With User Profiles (and on Windows NT):

<windir>\Profiles\username\Application Data\Microsoft\Outlook Express

Within this directory are folders for mail, and possibly for news and IMAP mail as well. The News folder has a subdirectory for each news account that is in use.

The Mail directory has no subdirectories, only a collection of files used to manage mail accounts. The three types of files in the Mail directory are:

MBX files. These files contain the text of all messages stored on the system.
IDX files. These files function as indexes for MBX files. The IDX and MBX files are always paired.
NCH files. These files are used to retain the folder hierarchy and to cache newsgroup and IMAP information.

Each IDX file has pointers to each message that is stored in its companion MBX file. The MBX files store the content of each message, including the addressing information. For HTML messages, the raw HTML source code is visible in the MBX file.

Inside the News directory, a folder is created for each news account. Two types of files are used to manage newsgroups:

NCH files. These files store a cache of articles downloaded from the server.
DAT files. These files store two types of newsgroup lists. The names of all current newsgroups are stored in Grplist.dat, while the names of all subscribed newsgroups are stored in Sublist.dat.

Outlook Express places data in two registry keys. User accounts and LDAP services are stored in:

HKCU\Software\Microsoft\Internet Account Manager\Accounts

Setting and configuration options are stored in:

HKCU\Software\Microsoft\Outlook Express