'Crazy - I love it!' An email from a trader who loved playing with the swagger of the financial markets just a little bit too much. Barclays' energy traders are accused of manipulating energy prices in California between 2006 and 2008.
The American authorities, the Federal Energy Regulatory Commission, have concluded that the alleged manipulation of the markets was so bad that the bank should be fined, £300 million, even more than they were fined for rigging the Libor rate, the scandal that forced Bob Diamond to resign.
And often in these cases, a trail of cringeworthy emails has been used by the regulator to build the case. 'Crazy - I love it!', one verdict on the volatility of the markets, 'you going to have fun with the index all month?' another.
Barclays however say they will continue to contest the accusations, and believe the trading was legitimate.
But handling this kind of controversy is a very big test for the bank's chief executive, Antony Jenkins.
He has made it clear he wants to change the culture of the bank and move on from the mistakes of the past. But that is harder to do when the bank is still stuck in legal tangles over traders' past behaviour.