Barbara: with regard to ISPs scanning email for viruses: I work at a medium-sized ISP which has very strenuous virus and spam filters. There are two major problems we hear about with this:

first, many customers get very upset about privacy and censorship if there is any indication that the ISP might be scanning their email.

second, customers get extremely upset if their legitimate business or personal email gets stopped or bounced because it inadvertently contains some pattern that matches spam filters (for example, having a Reply-To address at hotmail or yahoo which doesn't match the From address, while the subject line contains numbers or punctuation) or virus filters (for a few days during the summer, we blocked everything with the line "Hi! How are You!" for SirCam).

Jon: Virex is a very popular Mac virus-screener; I think Norton also produces a Mac version.

Chocolate Pi