USPS has been storing images of all envelopes delivered for many years now.
Prior to that, it was possible to have that information manually logged. If you corresponded with people in a Warsaw Pact country in the 1960s, that mail was recorded and sometimes opened.
Knowing a letter was delivered by USPS doesn't yield the contents. The state would have to subpoena each individual recipient - and they may have destroyed or lost the letter.
It would only be equivalent if every letter was opened and recorded so that all the contents would later be available because this subpoena covers not just emails but also drafted and deleted messages; any files in their Google Drive cloud storage services; any Google Voice texts. This isn't metadata the government is coming for, it is the full content.
Sometimes the contents almost don't matter. For example, if you saw multiple letters from an oncology department to a household, followed by letters from government departments and a funeral home, it wouldn't be hard to figure out what was going on.
It's the exact same problem with phone metadata. The connections can be made to tell the story, and are even easier to manipulate into whatever narrative the prosecution wants to sell.
In my example, you probably thought "person has cancer, household receives letters from the government post-death, bill from the funeral home", which is exactly how it could be sold. But it could just as easily be "person beating cancer, household receives government forms related to healthcare subsidies, funeral home letter was a condolence letter sent one year after the death of their parent." This is why metadata is so dangerous, it's far too easy to spin.
Just the same, I would feel a lot less violated if the government had header information for every email I received in the past year, than if they had the full email.
>USPS has been storing images of all envelopes delivered for many years now.
If this was of any doubt at all - they’ve made this accessible over email. If you enable “informed delivery” you get an email of the scan before it hits your mail box.
> USPS has been storing images of all envelopes delivered for many years now.
You mean those emails I get that the USPS claims it doesn't have an image for?
Oh don't worry they always have images of the blanket spam everyone gets. But actual mail with bills or letters? It's more usual to get "A piece of mail that we do not have an image for is included in today's mail."
Prior to that, it was possible to have that information manually logged. If you corresponded with people in a Warsaw Pact country in the 1960s, that mail was recorded and sometimes opened.