What happens next in this paragraph?

How to avoid the gmail spam filter
Create your own email list.
Rather than purchasing an email list from a third party or using a robot, build your list from scratch. The only people on your email list should be people who want to receive your messages.
Let your recipients double opt-in. Even if the only way to be added to your list is to sign up online, make sure your mailing list service delivers a confirmation message so the customer (or potential customer) can confirm their membership.