Because of the enormous avalanche of Spam mail you receive daily, a tool like Junkanoo 1.26 is very useful and practical.
It lets you view (in txt or HTML) the content of your mail directly on the server (before downloading it to your mail client), allowing you to test the emails that interest you, and those that are spam. Thus you can delete all spam emails on the server, and only download emails you want.
It also lets you configure the actual server blacklists and add spam emails that will in future be eliminated by the server.