A lead magnet is the incentive, whether it’s a free guide, discount, or tool, that convinces a visitor to hand over their email address willingly. It’s one of the cleanest ways to build a list because every contact has already shown genuine interest in what you offer. This matters even more when you’re comparing organically grown leads to purchased ones. Read more in what email leads are and why your business needs them. For benchmark opt-in data, see Mailchimp’s report.