New Outlook: how can I send attached files with it, from within File Explorer?

I need to attach files to an email using New Outlook, from within File Explorer.

In classic Outlook Desktop, I'd choose the files in File Explorer, right-click them, then select "Show more options", "Send to", "Mail Recipient".

However, this doesn't open a message in New Outlook, despite setting it as the default mail handler in Windows 11's System Settings.