Bring back the Cloudy to Cloudy Attachments
Outlook 2016 adds some fundamental attachment handling features that allow you by default to treat “links” to a shared cloud file as an attachment. This feature set is sometimes referred to informally as “cloudy attachments”. Other Microsoft mail clients such as the web clients for Outlook.com and Office 365, and the mail client that ships as a built-in app for Windows 10 will likely also support this feature set going forward.
The below linked document provides details on how the cloudy attachment feature is implemented, down-level and third party scenarios, and workarounds for one corner case problem with some builds of Outlook 2016.