I mean, not that it is a virus which spreads itself, but it is an email which persuades some recipients to spread it.
When they say "pass this on to everyone you know" that is a clue.
The virus-checkers are powerless against users.
See how effectively it has spread itself across the interweb
http://search.msn.co.uk/previewx.aspx?q="literally+millions+of+Esso"&FORM=CBPW&first=1&noredir=1
See also http://en.wikipedia.org/wiki/Chain_e-mail and http://en.wikipedia.org/wiki/Virus_hoax
When they say "pass this on to everyone you know" that is a clue.
The virus-checkers are powerless against users.
See how effectively it has spread itself across the interweb
http://search.msn.co.uk/previewx.aspx?q="literally+millions+of+Esso"&FORM=CBPW&first=1&noredir=1
See also http://en.wikipedia.org/wiki/Chain_e-mail and http://en.wikipedia.org/wiki/Virus_hoax