Sending email attachments via UWP EmailManager not working

I believe it is because the Outlook is a Desktop app. As I understood, the EmailManager.ShowComposeNewEmailAsync uses mailto: protocal to launch mail client app and use share to provide the email content.

If you choose the mail store app when the select default app dialog launches, you will be able to see the attachment as following:

If you have previously chosen Desktop Outlook app as the default as for mailto protocol, you have to change the default app for the mailto: protocol association in control panel .

Previously, the ShowComposeNewEmailAsync only works for windows phone runtime app. And it is not up-to-date in the document, because it doesn't include the win 10 support.

On Windows 10 mobile, it works well without any problem. But on Windows Desktop, you have to choose a store app.

This is still an issue in 2019, but I have found a workaround for my project. I simply assemble an *.msg file with recipients, subject, body, attachments etc. and save it to the apps local cache folder. It can then be launched using Launcher.LaunchFileAsync

As *.msg files are associated with outlook, it will most likely be the default app to open this kind of file. You can create such a file using MsgKit

I have prepared a demo project at: https://github.com/Moolt/UniversialWindowsPlatform.LaunchOutlook