NEW YORK -- In 2009, on April 25, a man named Greg is supposed to get an e-mail. It will remind him he is his own best friend and worst enemy, that he once dated a woman named Michelle, and that he planned to major in computer science.
''More importantly," the e-mail says, ''are you wearing women's clothing?"
The e-mail was sent by Greg himself -- through a website called FutureMe.org. It is one of the messages open to public view at the site, and Greg used only his first name.
FutureMe is one of a handful of websites that let people send e-mails to themselves and others for delivery years in the future. They are technology's answer to time capsules, trading on people's sense of curiosity, accountability, and nostalgia.
''Messages into the future is something that people have always sought to do," said Paul Saffo, director of the Institute for the Future, a research group. ''In a way, it's a statement of optimism."
Matt Sly came up with the concept for FutureMe.org about four years ago after recalling how, during his education, he had been given assignments to write letters to himself.
Sly, 29, who partnered with 31-year-old Jay Patrikios of San Francisco on the project, said the site has made maybe $58 through donations. He insists it is not a reminder service and that users should think in the long term.
FutureMe and others try to make the delivery process fail-safe through partnerships or backup software, and they urge people to hang on to their e-mail address, but there's no ironclad guarantee the message will ever arrive.
FutureMe lets people send messages for delivery as much as 30 years from now, though Sly's numbers show most users schedule their e-mails to be sent within three years.
''We want people to think about their future and what their goals and dreams and hopes and fears are," he said. ''We're trying to facilitate some serious existential pondering."
He said a large number of the messages do one of two basic things: tell the future person what the past person was doing at the time, and ask the future person if he or she had met the aspirations of the past person.
''The tone of the past person is not always friendly," said Sly, now a Yale University graduate student. ''It's often like 'Get off your lazy butt.' "
Recently, Forbes.com jumped on the idea, offering an ''e-mail time capsule" promotion. More than 140,000 letters were collected over about six weeks. Nearly 20 percent are supposed to land in the sender's in-box in 20 years, but others requested shorter time frames. Forbes.com is partnering with Yahoo and Codefix Consulting on the project. ''A lot of people have kind of been freaked out by it," said David Ewalt, a Forbes.com writer. ''It really makes you stop and think about your life in a way that you usually don't."