If Apple wants to be consistent about the App Store acceptance policy, it must reject every application.
Given that the reason MailWrangler was rejected is that
[The] application duplicates the functionality of the built-in iPhone application Mail without providing sufficient differentiation or added functionality, which will lead to user confusion...
and knowing that the Zawinski's law states that
Every program attempts to expand until it can read mail. Those programs which cannot so expand are replaced by ones which can.
The inevitable conclusion is that every application will end up "duplicating the functionality of the built-in iPhone application Mail" and thus must be rejected.