This is, obviously, an attempt to persuade the atacked person that the message comes from the legitimate source. The email address is the only information the phisher has, so it uses it.

But remember, a legitimate company will address you by the first and family name you registered with it, and not simply your email address.

The mentioned clues are apparent on this page, too.

The site uses Luhn's formula (a first step CC number verification algorhytm, which does not require connection to a CC server) to check the CC number you enter. Numbers that pass the Luhn formula test are accepted. This does not mean that the phishers have access to some CC info - this checking algorhytm is openly available.Of course, it CAN NOT verify whether this is a a real card number on its own.

After getting the information required, the phish site redirects to the legitimate wamu.com.