SMTP relies on MX records in the DNS to identify which server(s) it should hand the mail off to, and over 40 years after RFC722 was published, email is still cleartext.
Together, this means that any receiving mail server can trivially read any message passing through.
It used to be common for domain operators to run their own mail servers, but doing that is actually hard. And what do we do when things are hard? We pay somebody else to do it for us. To the cloud!
So I was wondering: how much is SMTP centralized in 2023?