Re: [arch-d] deprecating Postel's principle- considered harmful

[Rich Kulawiec <[e-mail]>]

On Tue, May 07, 2019 at 09:38:05PM +0100, Stephen Farrell wrote:
> Question for ya on that Barry - do you think that MUA
> and mail server implementers would actually bounce
> messages as strictly as Martin's document might call
> for? I'm not one of those implementers, so I don't know,
> but I'd not be surprised to hear that in fact they'd
> continue to prioritise mail delivery (for non spam)
> over protocol purity.

We *didn't*: back in the days when we were gatewaying messages between
the ARPAnet and CSnet and Usenet and everything else, we went out of
our way to shovel everything through no matter how awful it looked,
because we were happy (and relieved) (and sometimes mildly astonished)
that anything at all worked.

But now?  In the decades since, we've learned that every tiny opening
can be and will be exploited by someone, often in surprising ways.
The pendulum has swung a long way from "be liberal in what you accept"
because it's now dangerous.  When I think about Jon, and of what he
envisioned, I'm saddened by this.

But my sentiments aside, and all the history aside, anything new needs to
be nailed down as tightly as possible in specification and implementation,
because any gaps will be found and used.  Anything old needs to have the
holes fixed as best we can without breaking too much too fast.

Jon was right.  But the world is wrong, and now we have to cope with it.

---rsk