Someone or something has gotten into my address file and is sending "Undeliverable" e-mail in my name. I am receiving notices that what I have sent to various addressees is undeliverable. Anybody else having this problem?

Also, I have received several suspicious looking e-mails from address "chipsfromtrips". I didn't open them because the message read "You must open immediately", which, of course, I didn't. Why is that address familiar? Anybody know? Thanks. Chuck T.