Except that age is almost certainly already a variable in the rating system, and its effect should be taken in account already.

My comment was a little tongue-in-cheek, but you make a good a point. As other posts have mentioned, the email would be a proxy for other factors associated with age that age by itself can't capture.

If it's age at all. I'd bet it might be more closely associated with something harder to articulate or measure, along the lines of "a proclivity for clinging to subpar solutions." Someone who uses a subpar email service might also have ingrained poor driving habits.

Aaah, but it's not just age. It's also technical incompetence. People with Hotmail accounts are probably less likely to do their own maintenance, after all they haven't maintained their e-mail by moving to a provider with functional spam filtering. Their cars are more likely to break down. Not all insurance claims are due to accidents.