Honestly I wouldn't be surprised if the people that are contacting you are legitimately from that company. I've worked in marketing before and most companies will go to extremes to protect what they believe is their "brand image" or "brand reputation", no matter how inconsequential the supposed "infringement" is. They'll believe any misrepresentation of that "image" could/would/may impact their business.
Also, in my current job, I've received many emails from internal and external clients that have misspelled words, incorrect punctuation, etc., so unfortunately that has no bearing on the legitimacy of the email in question. Sad, but true.
Lastly what I don't understand though is yeah Brad isn't using the name in a business (i.e., selling products and/or services for profit), so I really don't get how they have any case whatsoever. I know Andy has said that trademark infringement isn't limited to commercial use, but still that seems silly. In that case, where does it end? Technically couldn't any person using a trademarked name in an email address, forum user name, gamertag, etc. be forced to change their name too, since they are "infringing" on the use of that trademarked word? Seems a little ridiculous to me.
Regardless, if you have to change your name Brad, can we refer to you as "The Artist Formerly Known as prophetik", or will that infringe on their trademark as well?