I'm using Mutt as an example, but there are cases when applications create a tmpfile, and use xdg-open on them. They assume that the helper application blocks until finished, then cleans up the tmpfile.
Problem being that assumption is false. At least in the kde-open case, it returns immediately, and the application cleans up the file prior to it actually being opened. kde-open does have a --tempfile option,
$ kde-open --help-kde-tempfile
--tempfile The files/URLs opened by the application will be deleted after use
Obviously, great care needs to be taken if using this, however.
See also downstream report,
Affects alpine, too.
I can no longer reproduce this with kde-open on kde-4.6.5 at least.
gvfs-1.6.6 seems to (still) have issues however, see