Interesting question this morning - Can I block all these viruses being mailed to me by email address alone ?
My first thought was, if the addesses are obviously bogus strings of random characters that manage to pass simple email address syntax checkers, you could trap them by applying Shannon's Entropy and detecting the randomness. But this may not work in email since many usernames and even domain names can appear to be entirely random, email@example.com for example.
I then started thinking about Benford's Law and the entropy of numbers and wondered if that could be applied to emails.
I have a small number of friends who email me frequently and a large number of aquaintances (and newsletters) who email me occasionally. The most anyone would ever email me in a day is 20x, and that is a case of spending way too much time conducting an all day email conversation. Being a boring stay-at-home type, my set of friends is unlikely to change, and any new friend will more than likely start off in the set of acquaintances before being upgraded. Strangers write to me from time to time, frequently its spam, although sometimes it is an aquaintance with a new email address, or a new newsletter I have subscribed too.
Therefore I should be able to deduce an algorithm predicting the frequency with which any given email address sends me email. Armed with this I should be able to construct an allowed message frequency band for email communication. If an email address suddenly jumps outside this allowed frequency band, then something is wrong. Either this is a spam, or a friend (or acquaintance has a virus). Either way I dont want this email in my inbox, but quarantined.
hmmm could work.