Microsoft used to do this. I worked in a startup with an exec a few years later and he admitted they did it. I think everyone does this. We had 10s of thousands

Microsoft used to do this. I worked in a startup with an exec a few years later and he admitted they did it. I think everyone does this. We had 10s of thousands of employees at Microsoft, and they'd send out these updates on windows status, like "the beta of the next release is coming in early January with these features". He said they could only vary it a little bit - I think it was spaces, maybe some dots, so an email to a large group would only have enough uniqueness to narrow it down to say 100 people. This must have been an old idea. I couldn't believe those reporters were naive enough to give up Reality Winner's original printout.