This is driving me crazy i'm re-posting this issue just to get more help.
recipients are having multiple e-mails upto 8 (when Symantic AV 0n)
and upto 22 copies (when Symantic AV is off)
The distribution list is set up in AD. The distribution lists include users (internal recipients) and contacts (external recipients). We have discovered that at this stage only some external recipients recieve duplicates and no internal recipients recieve duplicates. There seems to be no correlation between those contacts who are receiving duplicates (i.e. not on the same domain etc.)
We are useing,
Symantic Mail security for Exchange.
note: we already rebuilt the list few months ago .