The viruses use the infected computer's address book and
messages for both the "send to" and *"sent from"* addresses and
subject line. If the Histarch address is in the computer's address
book and messages, it can use that address as the "sent from"
address, looking like it came from Histarch when it didn't.
  There was a message, that someone alerted me to, that looked
like it came from me, with a message heading that I think was
recently on Histarch. There was second message that bounced to me
with my return address that I didn't recognize at all, either the
subject or the address it was sent to. Neither would be on my
computer for a virus to use. These messages both had viruses
attached.
  I have a one month old computer, with a brand new automatically
updated (every few days), Norton antivirus program. After I was
alerted by the receiver of the first message, I scanned my whole
computer. I do not have a virus. Someone on Histarch must have a
virus that's using the address book to both "send to" and "sent
from" that's using Histarch addresses and subject headings.
Marge Green