Anyone with an email address knows what inbox spam is. Probably, it’s a daily battle to make sure that spam is sent where it belongs – to the junk folder. Today’s spam filters do a great job protecting inboxes, but some unwanted emails still slip through. And sometimes, filters do their job too well; barring the marketing emails that people do want to receive. These acceptable marketing messages are called email whitelists. Whitelists are a form of very effective, targeted email marketing.