Because lead generation is the first step of the sales process, both quality and quantity are important factors. Quality leads are leads that a salesperson has a good chance of closing, which means they must at least have the potential to become customers. Every lead list will have a number of junk leads – people who are not qualified to buy the product for some reason – but the smaller the percentage of bad leads, the less time salespeople will waste while processing that list. Quantity is also important because even a salesperson with a list of 100% good leads won't be able to close every one of them.
When people talk about email marketing, lots of them forget to mention transactional emails. These are the automated emails you get in your inbox after taking a certain action on a website. This could be anything from filling out a form, to purchasing a product, to updating you on the progress of your order. Often, these are plain text emails that marketers set and forget.