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New outlook drag/drop support in Winforms

Peter Van de Putte 0 Reputation points
2025-08-27T08:58:52.57+00:00

We have a winforms application in which users could drag/drop mails directly from the old outlook, which would be processed using the outlook interop.

Since the switch to the new outlook, this drag/drop doesn't work anymore. I understood that microsoft wants us to move away from the outlook interop and start using the graph API.

I've debugged the drag drop event in winforms to inspect what happens and what data is available when drag/dropping a mail from the new outlook, and concluded that indeed none of the data contains the full mail object.

Following dataformats are available (which are all memorystreams)

  • Chromium Web Custom MIME Data Format
  • chromium/x-renderer-taint
  • DragImageBits
  • DragContext

The "FileDrop" data format seems to be available according to the e.Data.GetDataPresent(DataFormats.FileDrop) method, but when I call e.GetData(DataFormats.FileDrop) , the result is null

I've saved all the streams available in the data formats listed above, to inspect them using notepad, and the only one that contains a bit of mail data is "Chromium Web Custom MIME Data Format", but it does not contain the full mail data (no body, for example)

Are there any plans to re-add drag/drop support for emails directly from outlook into a winforms component (preferrably in .eml format)? What would be the timing in which this would become available again?

Or can we assume this will never be added again, and users must therefore first save the .eml file from outlook themselves, before drag/dropping it into our application?

Microsoft 365 and Office | Development | Other
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  1. Dora-T 4,105 Reputation points Microsoft External Staff Moderator
    2025-08-27T11:28:08.9633333+00:00

    Hi @Peter Van de Putte

    Thank you for reaching out to the Microsoft Q&A Forum and for explaining your scenario in detail.

    I understand how important drag-and-drop was for your workflow and how frustrating it must be to see this no longer working in the new Outlook. 

    Based on my research, it seems that the new Outlook does not expose full mail objects when dragging into external applications. The formats you’ve seen during debugging appear to align with the current behavior, and unfortunately I haven’t found any documentation or announcements suggesting that full drag-and-drop support (such as .eml files) will be brought back. 

    As a forum moderator, my role is to help guide discussions and share best practices based on publicly available Microsoft documentation and community knowledge. However, I don’t have access to Microsoft’s internal systems or roadmap, so I can’t confirm whether this functionality might return in the future. 

    I know this isn’t the answer you were hoping for, and I truly appreciate the effort you’ve already put into exploring this. I also understand how disruptive this change can be to existing workflows. If this functionality is important to your organization, I’d recommend submitting feedback through the Microsoft Feedback Portal. That helps Microsoft better understand what matters most to users. 

    Thank you again for your patience and understanding.

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

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