Gmail just turned 15 years old! Hard to believe that when it was announced on April 1, 2004, some people actually thought it was an April Fools' joke.
And now? Gmail's pretty much in charge of email. Don't count out Microsoft and Verizon (Yahoo), but most B2C senders will tell you that Gmail houses the largest single pool of subscribers that they send messages to.
And here's Google looking forward: Hitting send on the next 15 years of Gmail.