Share 'Coping with spam on multiple devices'

Here's a problem that some of us may be coming up against. I use a Mac Mini as my main (desktop)  computer; I run Mozilla Thunderbird on it as my email client.  Mozilla's not bad at coping with spam, and I've found the most powerful way to block spam is to use whitelists -- in other words, to tell the system that if the person sending me a message is not in my address book, that message is likely…