I finally received one that revealed a very old password sent in plaintext E-mail!‎
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Despite knowing that it's an empty threat, I did go password-cycle anything that was using that old password (some old accounts from when I didn't know better that I didn't bother to include in my regular rotation). It also got me wondering who was compromised. My E-mail address from my alma mater was used, which I haven't used to sign up for accounts in a very long time so this must have been a breach of a very old database.

On the plus side, the scammer provided a wonderful service: alerting me that a password is compromised and I should no longer use it.

Details of the scam: https://nakedsecurity.sophos.com/2018/07/13/sextortion-scam-knows-your-password-but-dont-fall-for-it/

On another note, I was trying to find the true source of that article. Duplicates seem to have popped up everywhere even on well-known news outlets but who was the original author?!