One way of minimising spam (unsolicitated email ie. junk email) is to configure one’s e-mail so that it will not accept mail from specified domains. As is well known, this is not a complete answer, since spammers can easily change address. Is it possible to configure one’s e-mail so that, instead of not accepting mail from specified addresses, it will accept mail only from specified addresses? Would it be possible, for example, to configure my e-mail so that it would accept mail only from addresses already in my address book? Might this also provide protection against e-mail’s carrying viruses? My operating system is Windows 98, my ISP is Bigpond and I also have a Hotmail account.

What you are saying really does depend on the circumstances. Most internet viruses these days replicate themselves and then email themselves to everyone in a user’s address book. This means that if you are in a friend’s address book and you have your email setup as you mentioned, the filters would not stop the virus from being received by you. However, if the virus came from someone you did not know, then the filters would provide protection. Whether you can setup an email clients filters to do what you want really depends on what email client you are using. I experimented with this in Outlook Express by setting up a filter so that ‘Where the From line contains people’ (and I put in a * value for that) ‘Delete it’. However, it seems that Outlook Express would not accept a wildcard like that and, even if it could, all emails would be deleted (even ones from friends). I suggest that you experiment with different combinations of filters and different email clients until you find one which can be setup like you want (but you will probably have to be pretty creative with the filtering!). I don’t think that Hotmail can do what you are asking.