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System requirements

GMSO is available for organizations running the full-featured version of Microsoft Skype for Business Online. We recommend that you use the Skype for Business client on Mac or Windows to participate in Skype meetings.

The GMSO add-in is an Outlook add-in for Outlook 2016 for Mac, Outlook 2013 and 2016 for Windows, and Outlook Web App. The CustomInvite is a COM add-in for Outlook for Windows 2013 and newer. Your hardware must match the minimum spec for those products.

GMSO add-in

Mac (64-bit)

  • macOS 10.11 or newer
  • Outlook 2016 for Mac


  • Windows 7 SP1, 8.1, or 10.
  • Outlook 2013 for Windows SP1 (32- or 64-bit), with the March 8 security update
  • Outlook 2016 for Windows (32- or 64-bit)
  • Internet Explorer 11 or newer


  • A Microsoft Exchange Online mailbox
  • Reading Pane displayed in Outlook for Windows, Outlook for Mac, or OWA
  • Permission to install Outlook Add-Ins via a URL

CustomInvite add-in

Windows only.

  • Windows 7 SP1, 8.1, or 10.
  • Microsoft .NET Framework 4 (Client Profile) or higher (Windows 7 and 8.1)
  • .NET 4.5.2 or newer (Windows 10)
  • Outlook 2013, 32-bit or 64-bit
  • Outlook 2016, 32-bit or 64-bit
  • Skype for Business client
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