Premise: Some of the emails had the subject line, "Think Twice." They were sent from a spoofed email address. The sender claimed to have had an associate plant a small bomb in the recipient's building and said the only way to stop him from setting it off was by making an online payment of $20,000 in bitcoin.
Hypothesis: Some of the emails had the subject line, "Think 1+1." They were sent from a spoofed email address.