New outlook (2024) drag drop problem

Question

New outlook (2024) drag drop problem

Marc Al 206

Hello,

I have an application where a user drops a mail (from outlook 365) and I make a copy of the mail) for archive purpose.
All is working perfectly but I have seen a message telling me that there will be a new outlook in 2024 (that I can try)

and it is not working anymore.

I have seen that I must use (in the Drag_Drop event)

if (e.Data.GetDataPresent("Chromium Web Custom MIME Data Format"))

{

}

But I have no idea what I can do with the result. Do you know where I can find information on the format? I have seen links with the source code of Chromium but I have no idea what to do with it in c#.

Thank you

Dave Cowley 10 Reputation points

2024-01-15T11:54:35.55+00:00

I have a similar issue, we drag and drop from outlook to Business Central to an extension which uploads to sharepoint.
David Spink 0 Reputation points

2025-02-09T23:20:29.98+00:00

Was any solution found? I also have the exact same problem only working in vb.net. I can find no information about how to handle "Chromium Web Custom MIME Data Format". This is preventing us adopting New Outlook as we are unable to drag invoice files out of emails to be automatically stored.

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Dave Cowley 10 Reputation points

2024-01-15T11:54:35.55+00:00

I have a similar issue, we drag and drop from outlook to Business Central to an extension which uploads to sharepoint.
David Spink 0 Reputation points

2025-02-09T23:20:29.98+00:00

Was any solution found? I also have the exact same problem only working in vb.net. I can find no information about how to handle "Chromium Web Custom MIME Data Format". This is preventing us adopting New Outlook as we are unable to drag invoice files out of emails to be automatically stored.

Answer 1

As I found this answer myself while experimenting with Outlook New, I will share my findings.

I posted C# code for parsing the "Chromium Web Custom MIME Data Format" here: https://stackoverflow.com/questions/68745902/what-is-the-data-format-specification-for-chromium-web-custom-mime-data-format/79941017#79941017

For Outlook New, this does not help much: the value is just a JSON string with metadata of the dragged mail.

If you want the real mail (or a mail attachment) as a plain file, you have to implement async drop.

This code sample demonstrates it: https://github.com/Nussbaum-Transportation/new-outlook-async-dragdrop/ (horrible interop code, but it works).

And .NET10 will bring async drop for WinForms applications out of the box: https://github.com/dotnet/winforms/issues/13422 which reduces the code amount for async drop to just a few lines.

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New outlook (2024) drag drop problem

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