[Email-SIG] Some parsing/generation issues of email in Python 3

[R. David Murray]

On Wed, 08 Jun 2016 23:42:31 +0900, "Stephen J. Turnbull" <turnbull at sk.tsukuba.ac.jp> wrote:
> It's a complete rewrite from first principles.  It's more robust in
> principle and more maintainable in practice, but faced with 100s of
> millions of emails (aka "tsunami of sewage"), the robustness can't be
> guaranteed.  I'm willing to bet it will converge to "robust in
> practice" much faster than the previous design did.

Except for the header folding algorithm in the new email policies.

I rewrote the compat32 header folder to be much simpler and more
maintainable, but the new policy header folder, which is much more
accurate and capable because of the improved header parser, is
unfortunately much too complex and opaque.  So that got worse from a
maintainability standpoint.  Rewriting it now that I understand the edge
cases better is high on my list of things to do, but we all know about
available time issues.... ;)

The header parser could also use some consistency cleanup, since it
evolved a bit during development, and there are many places where it
could be simplified, but despite those warts it is much better organized
and *way* more accurate and information-rich than the older parser
(which, frankly, was a very low-information parser).

--David