Usually I’ll reply to the sender and tell them they have the wrong email address, some don’t believe me, sometimes they ask me if I know the person (out of a billion gmail users), some complain that I took to long to tell them about the wrong address, and sometimes a lawyer will direct me to delete all copies of the errant email…
I always reply back to tell them that the email lands on multiple devices and is downloaded and backed up automatically and to see if they want to pay me on a time and materials basis or if they want a project based fee. None have been willing to pay me to cleanup their mistake.
Way back when I signed up with gmail, I was happy to get a first-initial.lastname@gmail.com address, now I wish I’d gone with something more obscure.