Every Card type comes with its set of reward and other features.
Today the systems that are in Bank are not geared up to change the type and keep the card number same. The reason being that for newer transactions they can still do it, however the historical transactions will become a mess, for example the rewards points calculated using older card type etc.
Hence its easier for Banks to issue a new card number, close out the old number and transfer whatever is the balance. This is more clearner and easier for existing card Systems in Banks.
Across Banks its just not possible for lot more reasons 

Change visa card type without changing number
Let's say I receive emails from the following clients:

mail2.dx300.mail.net
mail4.dx121.mail.net
mail5.dx121.mail.net

Even though these are all from the same service (e.g. LinkedIn or MailChimp), postgrey sees them as entirely different clients. How can I configure postgrey to just look at the domain (mail.net), not the FQDN?
