“Exchange” is an email server developed by Microsoft; the existing versions range from ES 4.0 (oldest) to ES 2019 (newest). The Trustifi add-in is supported on MES versions 2013 and newer. If you are not sure which MES versions you are using, you can consult this guide from Microsoft.
Why are only these versions of MES supported?
Only these versions support access to the Microsoft add-in store, where the add-in can be downloaded. This also grants the ability for the add-in to update automatically, without any action needed from the user.Older versions simply lack the security features (like automatic security updates) that the newer versions support.
Additional requirements (normally enabled by default):
Exchange Web Services (EWS) must be enabled and must be exposed to the Internet.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.