Edit: Dabs, there you go, pre-empting me while I am writing a post and multitasking:2. Snail mail is usually in sealed envelopes.
My general policy is that if you dont want to use end-to-end encrypted communications, which are easier to use than ever before (with so many things available that are easier than using gpg in the terminal!), it means that you do not want to talk to me. Bye! Although that is not always practical to enforce in business matters, I actually cut people out of my personal life over this.
...make even minimal effort to talk to you.
Reminds me of Snowden. He kinda forced the media who were trying to help him at the time he was escaping to Hong Kong or thereabouts (according to the movies about him); encrypt or don't say anything.
I would argue that in the case of PMs (private messages) on this board, only the admins can easily read them if they were unencrypted. Mods do not have that power. The whole site goes through https, so ... there is some encryption going on, just not really end-to-end person to person. So who can read PMs here? Basically theymos and a handful of other admins, and anyone who compels them to.
So encrypt your PMs, no one can read them for sure.
Still, those who I've worked with, tend to GPG encrypt stuff, or at least sign them when it involves addresses.
As for aliens, I'd wait until we have a small ring of solar panels surrounding our planet Earth ... Not exactly a Dyson sphere (since that goes around the Sun), but it should take care of our immediate energy needs in the near future.
It would probably start with solar panels on the ground too, or on the water. So much empty land and oceans.
Cloudflare.