I received an email from Shop4Miles.com saying that they are closing their mileage mall business in the next few days. They plan to switch to a different business model that won't give miles for shopping.
Until that happens, they are still offering 200 free Alaska, Delta, or Hawaiian miles with first purchase in addition to the miles per dollar they offer for the purchase.
Since all 3 airlines have multiple other mileage shopping mall options I would advise comparing any offer before buying using my site -
RewardsDB.com (other tools like the webflyer one don't list Shop4Miles offers or those from several other sources for these airlines so are not as useful in this instance).
All the dealings I have had with Shop4Miles lead me to believe they will honor any purchases etc prior to the closure of the mall site but I can't make any guarantees.