Anyone can send an e-mail purporting to come from an address other than their own - you can even do it yourself. Spammers often generate e-mail addresses at random, then fill in the "To" the "From" and the "Reply To" fields all with the same generated address, in the hope that it will (a) fool anti-spam programs, and (b) encourage you to open it.
It's not personal, and we all have to put up with it to a greater or lesser degree. Just bin it.