It called education. Some people like to give out their e-mail address to everyone so they know who they are and how important they are. Others like to keep large e-mail lists on their machines so they know how many people they know.
Others never give out e-mail address and keep very few in their address lists.
Guess who gets lots of infected e-mail when a new virus goes around, or who's system sends out lots of e-mail when it gets infected.
Educate your clients, not to give their e-mail address to everyone. Just those who really need it. Educate them to keep contact e-mail addresses written down, and not in an e-mail list on their machine. Keep their address boot very small, type the address in when needed. Don't give a virus something to work with. Set the FIRST e-mail address in the address book to name AA00virus and e-mail address to AA00virus. Note: no @ or period in e-mail address. If a virus infects machine, it may decide the list is not a valid e-mail list. If not, the address will cause a reject back to the sender and alert them to an infection in their machine.
Then educate them to encourage their contacts not to keep their e-mail address in their address either, but use the Reply to notes.
The case of multiple copies of e-mail sounds like an infected e-mail server that the original passed through. Good luck finding it.
Oh, and encourage them to remove all traces of the OUTLOOK program, and all of its code, from their systems and get a different e-mail program.
