Thats not my name.

There is a pet peeve of mine that I'm in a bit of a conundrum as to how to handle it.  People do not get my name right... ever.  Since I have known my own name, it has been mistaken for Nicole.  I thought it was because there was another Nicole in my grade school class, but she never got called Noelle.  So how do I handle this? Obviously I'm not doing it the right way because if I was there wouldn't be repeat offenses.  Usually, if someone first meets me and calls me Nicole by mistake, I correct them immediately. But what about someone you have known for years...like, oh, I don't know, your mother-in-law? Or what about co-workers?  I don't like to interrupt someone, but seriously, that's not my name.  Or the worst is at work when I'm in a meeting and someone refers to me as Nicole.  Last year, my boss, who knows how much it irritates me, stopped the meeting and corrected the offender.  Now that was embarrassing. I have to say the close second to the worst was when I overheard my now husband on the phone after we had been dating for at least two weeks say " Oh, I'm just sitting here with Nicole"  In his "defense" he claims that the last two girls he "dated" were both named Nicole. You can bet I haven't let him forget it.
Today however I received an email, that began "hi Nicole" after the person sent it to my email address, which btw has my name in it.  I responded to this by signing my name and putting a P.S.: my name is NOELLE. Guess what. He responded. It said. Thanks, Nicole.