Emails continue to bounce to me

Hi there, I've received increase notifications from people trying to send me emails to cox.net and the emails continue to bounce. Email error says the following: "eastrmimpi312.cox.net rejected your message. . . ." "the address you sent your message to wasn't found at the destination domain". Please explain what is going on - is this being sent to an east coast server when I'm part of a San Diego/west coast server? thanks,