Paul Tomblin wrote:

And stop people who subcribe to my
mailing lists from using Outlook and Outlook Express, so they don't flood
my mail servers with the viruses which they inevitably get because of it.

Stop people that happen to visit a web site or view a mail message with my
email address from using MSFT products. That would prevent those products
from sending out viruses forged to appear to be from me.

- Andrew