1971 A computer engineer in Boston sends himself a test e-mail on Arpanet, the precursor to the Internet.

The ability to send messages long or short in an instant is liberating. It also doesn’t leave much time for the kinds of second thoughts that occur while whiting out typos, sealing envelopes, affixing stamps, or walking to a mailbox. Here are some of the costliest moments in e-mail history.

From: Apple CEO Steve Jobs
To: Palm CEO Ed Colligan
Date: 2007

“We must do whatever we can to stop this.”

This line was part of an e-mail exchange among Apple, Google, Palm, Intel, and Adobe as they negotiated a moratorium on poaching one another’s employees. In 2014 the damning e-mails helped lead the companies to try to settle charges of conspiracy to hold down worker wages.

Cost: Pending. Federal Judge Lucy Koh struck down the preliminary $324 million settlement as too stingy.

From: Intel CEO Paul Otellini
To: Colleague
Date: 2006

“The best friend money can buy.”

Otellini was referring to Dell founder Michael Dell after the computer maker nixed plans to buy chips from Intel rival Advanced Micro Devices. In 2009 the state of New York accused Intel of bullying customers into using its chips and paying them not to switch to AMD.

Cost: Intel settled the case in 2012 for $6.5 million, without admitting wrongdoing.

From: SAP executive Léo Apotheker
To: Colleague Bill McDermott
Date: 2005

“We need to inflict some pain on Oracle.”

In 2005, SAP acquired a company that provided tech support to Oracle customers and downloaded its software and manuals without paying for them. Oracle sued in 2007, alleging that SAP stole its trade secrets.

Cost: In 2014, SAP agreed to pay $357 million in damages to settle.

From: BP engineer Brian Morel
To: Colleague Richard Miller
Date: 2010

“This has been a nightmare well which has everyone all over the place.”

This e-mail was sent six days before the explosion of the Deepwater Horizon oil platform off the coast of Louisiana, showing operator BP could have done more to prevent the disaster.

Cost: It was among several messages that helped persuade the company to enter into an ongoing settlement topping $28 billion.

From: Merrill Lynch analyst Henry Blodget
To: Colleague Eve Glatt
Date: 2000

“I can’t believe what a POS [piece of s-‍-‍-] that thing is. Shame on me/us for giving them any benefit of the doubt.”

Blodget was talking about Lifeminders, one of the many dot-com bubble startups that he publicly promoted. An SEC investigation later found he was deriding the companies in private.

Cost: Blodget paid about $4 million and was banned from the securities industry. He went on to found news site Business Insider.

From: Microsoft Windows head Jim Allchin
To: Chairman Bill Gates, CEO Steve Ballmer
Date: 2004

“I would buy a Mac today if I was not working at Microsoft.”

This e-mail came to light in December 2006, during a Microsoft consumer antitrust trial in Iowa.

Cost: Allchin, already on his way out, stepped down a month later. (Microsoft eventually settled with the state and didn’t disclose terms.)

From: SAC Capital portfolio manager Mathew Martoma
To: CEO Steven Cohen
Date: 2008

“Is there a good time to catch up with you this morning? It’s important.”

At the $14 billion hedge fund SAC Capital, Martoma was warning his boss that they were about to lose millions on a trade.

Cost: This e-mail became part of the government’s case against Martoma, who was convicted of insider trading and sentenced to nine years. Separately, SAC pleaded guilty and paid $1.2 billion.

From: Scammers
To: You
Date: Today

“My name is Danjuma Sule, one of the sons of major Gen Gumel Danjuma Sule, The late Nigeria’s former minister of mines and power in the regime of the late former Nigeria’s military Head of state, Gen Sanni Abacha.”

A typical Nigerian scam e-mail.

Cost: People around the globe lost $9.3 billion to this kind of fraud in 2009, according to researcher Ultrascan.

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