The Lean Startup: How Today's Entrepreneurs Use Continuous Innovation to Create Radically Successful Businesses · chapter 10 · id the-lean-startup-c10-03-hotmails-ps-i-love-you-get-you

“Hotmail's 'PS: I love you. Get your free email at Hotmail' footer is an example of viral engine growth, demonstrating how product usage itself can drive customer acquisition.”

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TechCrunch -- Viral Growth HacksFLAGGED: dead link (404)

Hotmail's viral footer is one of the most-cited growth hacking examples. The company grew from 0 to 12 million users in 18 months, partly driven by this mechanism.

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