I find MailWasher an essential tool allowing me to see all mail that comes to my accounts but ensure no spam reaches my Inbox. While many ISP's & mail services have their own spam filters MailWasher gives the user control to preview, accept or reject mail before it's downloaded. It removes the risk of spam filters stopping mail you actually do want but has rules to allow the majority of spam to be eliminated without any effort. I also use its preview window to read and process quite a lot of wanted email before it even gets to my Inbox!
MailWasher have released a YouTube showing their current beta in action. Although the new MailWasher looks quite different it works the same way as the current version. If you want to try the current release get it from Firetrust.com MailWasher. I can recommend it as one step toward "Inbox zero" is dealing with stuff before it even gets there!