Which One is More Important Product or Mailing List?
If you would ask this question, Which one is more important the mailing list or the product? any savvy marketer would answer you--The mailing list.

Principally, any wise business person puts the importance of hungry demand
(and not just any demand) in front of the product. In other words, there is no
product if there is no demand! And a mailing list represents the demand or your business if you would like to call it.
If you frequent Joint Venture forums and membership sites of any kind, you will
find that product and service owners need mailing list owners more than the
other way round. This is because the mailing list owners have the prospects that the other type of partner is looking for to sell to.
And if you are a mailing list owner, you do not have to necessarily make money
from selling your own product. You can sell advertising space or craft a Joint
Venture with product owners in return for commissions, recurring or not.

Many of the most successful web businesses on the Internet today often
establish the mailing list (or subscribers) first before the product.
potential friends from around the world through free membership access.

This book explains the tactics and tricks of having a newsltter.