Multi-domain mail message filters

I’ve been using mail filters to control spam as I haven’t found the other methods to be particularly effective. However, I’ve started getting spam on a second domain now, and it’s kind of annoying that I have to manually set up all the exact same filters again on the second domain.

Could you either make it easy to copy filters between domains or, even better, have a category of filters that apply to all your domains instead of just specific ones?