Morgan Willcock <morgan@ice9.digital> writes:

>   (url-filename (url-generic-parse-url "file:///c:/windows"))
>   => "/c:/windows"
>
>   (url-filename (url-generic-parse-url "c:/windows"))
>   => "/windows"
>
> This is relevant in functions such as
> mml-expand-html-into-multipart-related, where there is a check that the
> file exists:
>
>   (when (and (null (url-type parsed))
>              (not (zerop (length (url-filename parsed))))
>              (file-exists-p (url-filename parsed)))
>     ...)
>
> An example of a real world problem is being unable to reliably send HTML
> mail when using Windows:
>
> https://github.com/jeremy-compostella/org-msg/issues/122

Attached a potential patch.