I asked a few friends whether they'd had this happen, then looked up the popularity of their initials/names over time.  Based on those numbers, it looks like there must be at least 750,000 people in the US alone who think 'Sure, that's probably my email address' on a regular basis.

"Reverse Identity Theft", by Randall Munroe, licensed under Creative Commons Attribution-NonCommercial 2.5 License

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I asked a few friends whether they'd had this happen, then looked up the popularity of their initials/names over time. Based on those numbers, it looks like there must be at least 750,000 people in the US alone who think 'Sure, that's probably my email address' on a regular basis.