Lulu is changing their mature content listings so that book will mature content will be effectively invisible except through direct links you provide to specific customers.
"This means that content rated Direct Access is restricted to customers you select. You will receive a web URL at the end of the publishing process. You can then send this link to the people you want to see and purchase your work. Direct Access content is not searchable on Lulu."
[Thanks to Dusk for mentioning this change at ERWF.]