Outlook Express

Outlook Express is an e-mail and news client, originally released as Microsoft Internet Mail and News with Internet Explorer 3 in mid-1996. With the release of Internet Explorer 4, the program was improved and renamed to Outlook Express - it was included with Windows under that name since Windows 98. It was also available for Windows 3.1x, Windows 95, Windows NT 3.51, and Windows NT 4.0. It was discontinued in favor of Windows Mail found in Windows Vista, which was itself then replaced with Windows Live Mail with the release of Windows 7, and later with a new modern app in Windows 8, 8.1, 10 and 11.

People often confuse it with Microsoft Outlook, a similar program bundled with Microsoft Office since Office 97, and hence think Outlook Express is a stripped-down version of Microsoft Outlook. However, that is not the case as the two programs do not share a common codebase.

Pre-release
An early version of Microsoft Internet Mail and News, codenamed "Athena PIM" is included in Windows Nashville build 999.

Microsoft Internet Mail and News 1.0
Microsoft Internet Mail and News was initially released in mid-1996 with Internet Explorer 3. This version is the first to include the "MORTIMER" easter egg. Open the About dialog, click in the version table on any file listed there and type MORTIMER while holding the ⇧ Shift key. It is also available in version 2.0 and early versions of Outlook Express 4.0.

Microsoft Internet Mail and News 2.0
Microsoft Internet Mail and News 2.0 was released later in 1996 with Internet Explorer 3.02.

Outlook Express 4.0
Outlook Express 4.0 was the first version to carry the Outlook Express branding as part of Internet Explorer 4 in 1997.

Outlook Express 5.0
Outlook Express 5.0 was released in June 1999 and was bundled with Internet Explorer 5.0/Windows 98 Second Edition.

Outlook Express 5.01
Outlook Express 5.01 was released in February 2000 and bundled with Internet Explorer 5.01/Windows 2000.

Outlook Express 5.5
Outlook Express 5.5 was released in June 2000 and bundled with Internet Explorer 5.5/Windows Me.

Outlook Express 6.0
Outlook Express 6.0 was released in 2001 and bundled with Internet Explorer 6/Windows XP.

Outlook Express 7.0 and replacements
Outlook Express 7.0 was seen in pre-release builds of Windows Longhorn (Vista), which would indicate that Windows Vista was to have Outlook in the final RTM build. However, with the development reset of Longhorn, Outlook Express 7.0, along with the WinFS feature heavily needed for it were both scrapped and replaced with Outlook Express 6, which became enhanced in later builds and then evolved into Windows Mail. It features a similar layout to Outlook Express 6. You can find Windows Mail in Windows 7 pre-releases, though being intentionally broken in later builds. Later, it was completely scrapped from Windows 7 and instead, it was moved to the Windows Live Essentials suite, being enhanced with various features (most notably the integration in other Windows Live services), and became Windows Live Mail. Windows Mail should not be confused with the modern Windows Mail app that is present on Windows 8, 8.1, 10, and 11 systems.