> the full implications must be understood and carefully weighed before choosing a different course.
Note the use of the word "must" used twice there. Barring a sufficiently good reason and accepting the consequences, this becomes a very poorly worded "required".
The spec would have been far better starting with SHALL and then carving out the allowance for exceptions.
No, its not a "required"... It means someone may have reasons not to use something, and so spec implementors need to allow for circumstances where it is not present.
Those reasons can be anything. Legal, practical, technological, ideaological. You don't know. All you know is not using it is explicitly permitted.
"permitted" is a pretty empty word in the given context. Because dropping such emails is equally "permitted". Sure, there will be no arrests made, but there will be consequences. And those are what this article is about.
If that's your line, then I am equally permitted to send random binary blobs along the way. Not a crime, so totally permitted. They'll just drop the connection.
Buuut I don't think that is at all relevant to the discussion at hand.
> You don't know. All you know is not using it is explicitly permitted.
In theory, if they are truly following the specification, you know they thought hard about all the consequences.
I think the pushback in the comments comes from the commonsense feeling that this... didn't happen here.
I don't even know how you got to "used twice" tbh. Both your own comment AND the post you quoted from only have a single "must".
The only thing that text demands is understanding and carefully weighing the implications. If, having done that, you conclude that you don't want to then there is absolutely nothing in the spec stopping you. Maybe the spec would have been better off putting more stuff in SHALL and less in SHOULD, but as written that is definitely not the case.