It's not working, but not because the standard says you must support a much more lax format. It's not working because some people are writing bad code, that cod

It's not working, but not because the standard says you must support a much more lax format. It's not working because some people are writing bad code, that code does not only fail for spaces between quotes. It fails when more than 50% of the world tries to use their native alphabet - when using UTF-8. It's not the standard's fault that people implementing are not following the old adage of implementing standards: "Be strict in what you give, be lenient in what you accept." Considering how there's really not a tremendous amount of variety in what e-mail software people use, it boils down to those maintainers' stubbornness. If you dig trough old mailing list threads and issue tracker tickets, the ossification becomes quite visible.