A doubt theres a way of finding out appart from emailing them back and asking them. There will be data protection stopping the email provider telling you & they may not know anyway as anyone can setup disposible email account's with no ID. Allso peopel can mask there IP adress or change it each time. If theres a seriuos criminallity involved maybe the Police would try but a doubt theyd find anything
You can allso cant rely on the email adress shown on the email as senders can spoof that, but you can sometimes get info the real email adress by veiwing the email raw message