There are these little things on your server, you set them up once - then a long time passes - and then you realize, it is really helping you a lots and (most importantly) it is still working.
One of these things for me is how I handle Spam/Ham on my IMAP server. I had initially the idea to automate this as much as possible and let the computer/machine do the work (and I don't have to worry about it anymore).
I have a number of IMAP folders, obviously "INBOX", "LearnAsHam", "LearnAsSpam" and "Spam". If I have an email in my "INBOX" what is spam I'll move it into "LearnAsSpam". It will be picked up by a process I'll explain later and moved into "Spam". If there is a false positive in "Spam" I move it to "LearnAsHam" and after a process picks it up it ends up in "INBOX" again.
And this "process" is basically fetchmail feeding it through sa-learn with "-spam" or "-ham" as its parameter.
The relevant shell commands I think I got from here. A bit of a biest, but they'll work.