So how do they do a preheader? The first sentence in the inbox preheader is SELLING.
I can't stand the "problems viewing" pre-headers that dominate the marketplace today (like the one below from Costco).

Once you open the message on the iPhone, that pre-header is a clickable link. And that link takes you to a landing page that while not optimized for mobile, is actually pretty good.

Here's the landing page for the preheader link.

Now check the Costco message.

The landing page for the main offer, is a landing page optimized by internal search.
If you view on a mobile, you really should have bigger images. And also, think about formating so that you take the up the full screen and not waste space on the right, like the Costco landing page below.
