Outlook add-in requirements

For Outlook add-ins to load and function properly, there are a number of requirements for both the servers and the clients.

Client requirements

  • The client must be one of the supported applications for Outlook add-ins. The following clients support add-ins.

    • Outlook on the web for Exchange 2016 or later
    • Outlook.com
    • new Outlook on Windows (preview)
    • Outlook 2016 or later on Windows
    • Outlook on Mac
    • Outlook on Android
    • Outlook on iOS
  • The client must be connected to an Exchange server or Microsoft 365 using a direct connection. When configuring the client, the user must choose an Exchange, Office, or Outlook.com account type. If the client is configured to connect with POP3 or IMAP, add-ins will not load.

Mail server requirements

If the user is connected to Microsoft 365 or Outlook.com, mail server requirements are all taken care of already. However, for users connected to on-premises installations of Exchange Server, the following requirements apply.

  • The server must be Exchange 2016 or later.
  • Exchange Web Services (EWS) must be enabled and must be exposed to the Internet. Many add-ins require EWS to function properly.
  • The server must have a valid authentication certificate in order for the server to issue valid identity tokens. New installations of Exchange Server include a default authentication certificate. For more information, see Digital certificates and encryption in Exchange 2016 and Set-AuthConfig.
  • To access add-ins from AppSource, the client access servers must be able to communicate with AppSource.

Add-in server requirements

Add-in files (HTML, JavaScript, etc.) can be hosted on any web server platform desired. The only requirement is that the server must be configured to use HTTPS, and the SSL certificate must be trusted by the client.

See also