Some trivia about Outlook version numbers;

1. Microsoft Office Version 16
2. Microsoft.office.interop.excel Version=15.0.0.0

• What are the version numbers of Outlook and their released names?
• Why does it start with version 8.0?
• Why is there no version 13.0?
• Why isn’t Office 2019 version 17.0?
• What are the build numbers of the Service Pack releases?

Version Names and Version Numbers

Microsoft Office for Windows 10 PC: Download Microsoft Office for Windows 10/8/7 64-bit/32-bit. Safe and secure download! Microsoft Office is one of the most popular Office and Business Tools apps nowadays! Install Microsoft Office latest official version on your PC/laptop for free. Microsoft Word, Excel, PowerPoint, OneNote and Outlook. Could not load file or assembly 'Office, Version=15.0.0.0' I've Devoloped Software using VB.Net And I used ( Microsoft.Office.Interop.Excel ) Library in it Now I want to use this Software in other Computer Which have No excel installed in it.

The version number of Outlook relates to the first 2 numbers of the entire build number as reported in Outlook’s About dialog. side from Outlook 98, this second number is always 0.

You can look up the build number of Outlook in the following way:

• Outlook 2007 and previous
  Help-> About Microsoft Office Outlook
• Outlook 2010
  File-> Help-> About-> Additional Version and Copyright Information
• Outlook 2013, Outlook 2016, Outlook 2019 and Microsoft 365
  File-> Office Account-> About Outlook

An overview of the released versions of Outlook and their version numbers;

This version number is used for stamping the installation files of Outlook and is also used in the Registry, with the most known Registry hive being;
HKEY_CURRENT_USERSoftwareMicrosoftOffice<version>Outlook

Office 2019 is not version 17.0?

As you can see, since Outlook 2016 the version number is stuck at 16.0 and Office 2019 didn’t become version 17.0. This is because Office 2016 and Office 2019 now use the same code-base as Microsoft 365 and your license determines which features are enabled.

At the same time, this change also increases (or to be more technically correct; doesn’t decrease) compatibility with add-ins and external applications which explicitly look at the version number.

Background info

Outlook was first introduced in Office 97 which had the version number 8.0. The version numbering of Office itself skips number 5 and 6. This is because since Office 95 (version 7.0), all Office applications started sharing the same version number. Word at the time was in its 6.0 version and with that it had the highest version number. Its next version for Office 95 would become version Word 7.0 so that version number was taken for the entire Office 95 suite.

Outlook 97 replaced the applications Schedule+ and Exchange Client which were previously bundled with respectively Office and Exchange Server.

Before Outlook 97 there were already clients called Outlook bundled with Exchange. Their names are; Outlook for MS-DOS, Outlook for Windows 3.x, and Outlook for Macintosh. After “Microsoft Outlook 2001 for Macintosh” came Entourage which offered Exchange connectivity for Mac users. All these versions have their own version numbers which have nothing to to with the current versioning scheme.

Outlook 98 was initially a free download and later remained as a free upgrade for Outlook 97 users adding new features – most notably support for non-Exchange accounts. Its availability has been pulled shortly before the release of Outlook 2000. As its release was outside the normal release cycle of the Office suites (to which the version numbers have been tied), the version number of Outlook 98 could not be a full version higher than Outlook 97.

No version 13.0

At the MVP Summit in 2009, Steve Ballmer admitted (to little surprise) that there won’t be a version 13.0 for any of the Office applications because of “plain old superstition”. However, he also said that there is no “company policy for superstition” and that other product groups may release a 13.0 version of their product in the future. Obviously this superstition isn’t going to be localized for other markets where they would fear the number 14.

Other current uses of the Outlook brand

Outlook on the Web is the Web-based e-mail interface of Microsoft Exchange Server. Initially it was called Exchange Web Connect but soon replaced with Outlook Web Access. In Exchange 2010 and Exchange 2013 it is called Outlook Web App and was renamed to Outlook on the Web with Exchange 2016. As it is a part of Exchange, the Outlook Team doesn’t develop it. However, the release cycle of Exchange is synchronous to the Office Suite and shares the same version number since Office 2010.

Since Office for Mac 2011, Outlook replaced Entourage but has a completely different development team (they are even located in a different State!) and originally another development cycle. While it does share the same version number, originally, Office for the Mac is released 1 year after its Windows counterpart. This is no longer the case since Office 2019.

In August 2012, it was been announced that Outlook.com would replace Hotmail. While Outlook.com takes over some design elements of Outlook 2013 and OWA 2013, this was also managed by a completely different team. Taking Outlook.com into production is part of the “Wave 15” project which again matches the version number of the Office releases. As of mid-2017, all Outlook.com mailboxes are hosted by the Microsoft 365 platform and is very similar in look and feel to the corporate Outlook on the Web experience as part of Exchange Online. For various new end-user features and changes, Outlook.com often is used as a test-bed for the corporate version.

Build Numbers

The exact build number of Outlook that is shown in the About dialog relates to which updates have been installed. This often helps with troubleshooting and is also referred to as “patch level”.

Microsoft Office Version 16

Below you’ll find an overview of some of the major build numbers.

Microsoft.office.interop.excel Version=15.0.0.0