Drag and drop email from Outlook to Edge results in a warning dialog. Stable 81.

Dear reader,

A coworker of mine reported this morning that the drag and drop experience from Outlook 2016 (o365) to a Web app running on v81 stable changed from v80 stable.

If he drags a email from Outlook to the Web app (in this case TopDesk but also Sharepoint shows the same behaviour) it results in the  warning dialog in the bottom of Edge "This type of file can harm you computer. Do you want to keep "filename" anyway?", not the mail message file being uploaded. This worked well with v80 stable.

Does anyone seen this behaviour and has a clue what the cause could be?

regards, Henno