The cause of this issue has been identified; a fix is in development and expected to be deployed within the next 7 days.
Posted Jul 07, 2020 - 11:40 PDT
We are investigating an issue of being unable to drag & drop emails from Outlook into Smartsheet. If the file is saved locally on your computer (having first drag & dropped the email onto your desktop) it can then be uploaded into Smartsheet successfully. We will provide an update as new information becomes available.