Interesting Fact # 1004 - Google Mail

Google has adapted its free email service so that users can adjust their email settings to activate a feature that makes you solve a few simple math problems after you click "send" to verify you're in the right state of mind.

(It's to prevent anyone from letting loose after having had a few too many, just to make sure you really want to tell your boss what you think of him / her. Not recommended for anyone who is mathematically challenged though.)