How do I stop someone from using the same email address?

Block their email or put them on your spam list.

You can block the email address

It is not possible for someone else to have the same email address with the same domain name. Like there cannot be two people addressed as ME@yahoo. The email messages you receive are modified to deceive you -- your own email address appears as the sender's address? Is that the situation? If so, it is a common method used by big-time spammers to hide their return address.

It's called spamming!! It's people like me who are asked to provide a email in order to sign up for something for free or to get a free offer- it's people like me who just type in any common email and let that poor sucker deal with all the spam that come for years and years. For example, you know that out there that someone is using the email: let's see, let's try this one: [email protected] Why should I get spam when I can just send it to someone else!!! P.s. I know I'm bad. and apologies to all if I use your common, famous email.

They don't have the same email address as you, they're just using your address in the "From:" header in order to fool your email client into accepting the message as legitimate.

Well Some One From Your House Is Making You Fool Or ANy Friend Of Urs Who Know Ur PAssword IS Doing IT http://answers.yahoo.com/question/index?qid=20080909143632AAoWyte Plzz Answer THiss I Really Need HElp

select "mark as spam" or send to spam folder to block the incoming address

Your email service should have a block address option.

block the e-mail address. There is usually a button for this on your e-mail account.