I get quite a few misdirected emails, probably because my email address is a very obvious one for someone with my name.
My most prolific alter-ego is some chap in Canada — I get quite a lot of stuff for him relating to little-league baseball and the Democrat party. I usually respond to these mails politely asking them to check their recipient’s address and usually they say “oh, thanks” and sort it out.
My most annoying one is a chap in Australia who runs a small business and gets his tax-related mails sent to me(!). I’ve tried repeatedly to get the accounting firm to change the address (or at least check it with him) but to no avail.
The ones that are my favorite though are the ones who are convinced that I must be the person that they think I am, despite my overwhelming evidence to the contrary. These sometimes take several rounds of email to reach a satisfactory conclusion.
Anyway. This is all really to say that your situation sounds more like an accident than malicious intent. The trouble really is sorting it out: you need someone on the other end who has another vector of communication with the “other” stevextc and who is willing to tell them “hey, you fat-fingered your email address, over and over — sort it out”.
EDIT: I’ve just realised you mentioned you now have his/her address. You could even write to them (snail mail)?