DO NOT OPEN SUCH EMAIL.
Sorry to yell that, but a new type of SPAM as well as E-mail virus/trojan/others attempt to get people to open such E-mails to infect your machine.
Again, it's likely just SPAM or some virus/trojan on someone else's machine.
It's 99.99% certain you didn't send such emails.
I have Earthlink for my e-mail and am happy with it. However, in the last few days I have had e=mail "returned to me and I have not sent it. I reported this, but do not understan the gobble-degoop the use to try to solve my proble. Iuse an AMD with 2Gigi-bit drive. OS Windows XP sp2. Computer scans virus free with Norton and Panda. Any ideas? I can not find any hidden adress.