Listbuilding is foundational to any online business. When you your list, you always have a welcome audience, but be sure to not just sell, sell, sell to your list. Provide value. If all you do is promote to your list, then will eventually unsubscribe or ignore your emails. By providing value it show you as knowledgeable and they will want to see what your emails have to offer. Of course even when you are providing the value you can include a PS with your promotion it in. I too use LeadsLeap as my primary marketing tool because not only does it have a listbuilder but lots of tools that a marketer needs. I am a pro member there, but free or pro it is the best.