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.
Think Twice was a warning.
There was no real warning. The subject was to tell people to send the payment. The system isn't sure because it could be interpreted as a warning.
( z1 warn :ARG1 ( z2 think :frequency 2 ) )