The recipient you are sending email is most likely infected with the Netsky virus.
"W32/Netsky is a family of mass-mailing worms that spread by email using addresses obtained from the infected computer. They have their own SMTP delivery engine that sends infected messages directly to the recipient's mail server. It also spreads via local networks by trying to copy itself to shared folders on drives C: to Z:. The worms randomly select an address as the "From:" address: therefore the apparent sender of the infected email is not the real sender and their computer is probably not infected.
The subject header of the message is randomly chosen from a large number of strings. The message text is also randomly chosen. In most cases, the message is meant to look like a system generated message, such as an error report from a mail server.
The worm is contained in an executable file attachment, whose name is also chosen from a large number of possible names. It may or may not have a double extension (like mp3.pif) and it may be contained in a Zip or Rar archive, which in some variants may be password protected.
When activated, the worm may display a message. The worm then copies itself to the hard disk and installs a Registry entry so that it is run automatically at startup. The worm then executes this file in order to propagate using the methods described above.
W32/Netsky variants remove registry values in order to deactivate some earlier viruses, if present. Some variants may initiate a denial-of-service attack on certain websites at certain periods, others can be used as a backdoor into the system if not blocked by a firewall.
W32/Netsky.V installs an FTP server and a web server on the infected computer, which can be used by an attacker to obtain information about the system or install other malicious software, once alerted by an email sent by the virus."
[Source:
Tech-Pro.net ]
You can download a removal tool from
Symantec
I had the same problem, i was receiveing/sending out those emails, without my knowledge, but after running the removal tool, everything went back to normal and get rid of this ugly virus.
Take care
