I just browsed while logged in to my amazon account. Here's the body of the email:
Dear Amazon.com Customer,
As someone who has shown an interest in exhaust parts and accessories, you might like to know about our special opportunity to save an extra 25% on Magnaflow performance exhaust products with a limited-time promotional code.
Your promotional code is [omitted]
This promotional code can only be used once and is unique to your Amazon account. It is valid through April 30, 2013, while supplies last. This offer only applies to Magnaflow products sold and shipped by Amazon.com, and does not apply to items sold by other merchants on the Amazon.com website.
To take advantage of this special offer, use our Part Finder to choose Magnaflow products that fit your vehicle. Then enter your promotional code at checkout. It will be applied to the two lowest-price Magnaflow items in your Shopping Cart.
Thanks for being an Amazon.com customer.