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.
![If your email address is [first initial]+[last name]@gmail.com you gradually get to know lots of older people who have the same name pattern [[A figure stands talking on the phone.]] Figure: Yes, I know it would make sense if that were your email address, but it's not. Phone: But how did you get my number? Figure: Your phone bill.](https://imgs.xkcd.com/comics/reverse_identity_theft.png "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.")