If you can make it through the math, your message goes on its merry way, and you can continue to e-mail without further checks, although there's no stopping your text messages. But if you have difficulty solving "5 times 2" or "94 minus 33," you're gently chastised by your e-mail: "Water and bed for you" or "Oops. Looks like your reflexes are a little slow," if the time runs out.
Regardless of why you fail the test, a sympathetic Gmail feels your pain and offers you the chance to try again.
By default, Mail Goggles only "Breathalyzes" you on the weekends between 10 p.m. and 4 a.m. But once the program is enabled, users can adjust when it's active as well as the level of difficulty. The program won't reach math of Pythagorean proportions, but it does let math whizzes raise the bar to keep themselves out of trouble.
In announcing the feature on the Gmail blog, Gmail engineer Jon Perlow wrote, "Sometimes I send messages I shouldn't send. Like the time I told that girl I had a crush on her over text message. Or the time I sent that late-night e-mail to my ex-girlfriend that we should get back together.
"Hopefully, Mail Goggles will prevent many of you out there from sending messages you wish you hadn't," he wrote.
Both "Undo Sent" and Mail Goggles are free applications for Gmail, which is also free.
Not to be outdone, developers of iPhone and iPod applications, with programs that do everything from count calories to translate foreign languages in the palm of your hand, have created a number of features to keep you from making drunken screwups.
Apple began Wednesday selling the Bad Decision Blocker, an application that lets users block the numbers of people (such as an ex-boyfriend) saved in their phone's address book.
"It lets you select the person you'd like to block and then set the duration," said the app's designer Dan Burcaw, the CEO of Double Encore.
"It takes that person's e-mail address and phone number out of the address book entirely. It puts it in a secret place that is not readable," he said.
The app sells for 99 cents at the Apple Store's Web site.
Perhaps the most ambitious device to keep you from doing something really stupid is the iBreath, a breath-test device that attaches to your iPhone or iPod.
Users blow into the iBreath and a readout of their blood-alcohol content appears on the phone's screen.
"All kinds of people are using it," said developer Don Bassler, CEO of David Steele, the iBreath's manufacturer. "Parents of kids, college students, wives for husbands, boyfriends for girlfriends. The demographic starts dubiously as low as 16, but is basically the 18 to 50 crowd."
The iBreath debuted at Christmas and, according to Bassler, the company has sold thousands of the devices. It retails for $79.99 on the company's Web site.
"People listen to their iPods more than they listen to their parents or friends who might be trying to give them good advice," he said.