Wow what a detailed, well-written and fascinating response. Thank you for writing that, I thoroughly enjoyed reading it.
It would almost be worth putting #2 to the test, just to see what would happen. As you mention it would be a legal minefield.
Interestingly (and I guess this is the same in the US?), it’s illegal to open someone else’s mail. For sure Law Enforcement could get around that, but they would need a court warrant and you’d have to pity the judge whose desk that landed on.
The law states:
84 Interfering with the mail: general
A person commits an offence if, without reasonable excuse, he—
intentionally delays or opens a postal packet in the course of its transmission by post, or intentionally opens a mail-bag.
I think that if the package was innocuous (i.e. didn’t have <b>Jeff’s Gun’s By Post </b> emblazoned on it with a drawing of a strutting Texan blowing the smoke from his revolver), then it could be tough to find “reasonable excuse" to open the package.
Joking aside, if the recipient was a known member of forums promoting hatred or violence then it could be considered reasonable to make at least a cursory examination based on “why was this package received from from there?”.
It’s legislation with good solid intent (IMHO), but it’s so vague that it can’t cover everything.
Nor yet anyway.
As we come from different nations, our feelings on the matter may differ and I don’t really want to discuss that. But thank you, you’ve made it easier to understand the context.