Okay, what also happens is if I do: exo-open mailto:foo at bar.com "To:" in icedove gets mangled to "mailto:foo at bar.com", where it should be "foo at bar.com". The problems appears to be the same as in bug #720377 http://forum.xfce.org/viewtopic.php?pid=31575 https://bugzilla.xfce.org/show_bug.cgi?id=10098