Drag and Drop directly from Outlook to a webform
The easiest solution I found is to just create an Add-In for Outlook to add the email to our database.
I found this sample WebApp where you can drag and drop Outlook Contacts to an HTML5 WebForm.
If you drag an Outlook Message directly from Outlook to the WebForm you can drop it, but nothing happens. Maybe with a little tweaking you can get it to work with Messages too.
regards
AT this moment drag-and-drop API in Internet Explorer Browser isn't supported, Microsoft will implement it in IE 10, but i don't know if Drag-And-Drop API will bring you with the functionality that you are looking for.
HTML5 Drag and Drop in IE10 PPB2
For the rest of browsers the API implementation is incomplete
i recomend you to considere alternatives to this approach