This can happen for a few reasons. Do you see someone else's email address in the To: line, or your email address and someone else's name? Sometimes email marketers and spammers will send an email To: one address and BCC: many other recipients of the email. It could also be that someone has a bad address book entry for you. If you check the email you should be able to decide for which reason it's not your name in the To: field.