One of the first things you learn in Journalism school is that you can never, ever, under any circumstances, ever spell a name wrong. You check the spelling of Every. Single. Name. Even if it's something that should only have one spelling. "Amy" can be spelled "Aimee." "Tom" can be spelled "Thom."
People generally only have this pet peeve if they have a commonly-misspelled name.
So people with names like, I don't know, Ben, for example, don't get that it's annoying to address people with the name "Kristin" as "Kristen" in e-mails.
I think e-mails are the most annoying place to spell a name wrong because it's right there in front of you.
I literally just e-mailed you and signed it "Kristin," and then the first line of your response is "Hey Kristen?" Really?
Just pay attention!