Now that I’ve nearly got the settings right for Spam Guardian, I’m really pleased with it. I’ve had the filter sensitivity set to "5", which has screened out around 80% of the spam mails. Some are still getting through, though, so I’ve increased the sensitivity to "strict", which has a scalar equivalence of "4". If this correctly tags all the unwanted mail, then I’ll get it to delete the mails at the server before they get sent to my inbox – but only after a trial period (perhaps a week) of simply tagging the offending mails, just to be sure that I’m not going to screen out anything that I actually want to receive.
Exciting, isn’t it?