Leaving money on the table

On August 1 two domains in the Netherlands are going away: wanadoo.nl and orange.nl. Current users of these domains are being transitioned to new addresses at online.nl. Mailchimp has more information and links.
This is a good time for all of us to consider how easy it is for a subscriber to change their address of record. Some senders just have the subscriber unsubscribe from one address and resubscribe for another. This sounds like the simplest way to do things, and it certainly doesn’t take much engineering effort.
But what information do you lose by simply asking subscribers to unsubscribe and resubscribe? It depends on what you’re tracking, but you do lose everything that you track. Preferences, interaction history, purchase history, it’s all gone. Providing a simple way to change an email address of record preserves the information related to that subscriber.
For some senders, keeping subscriber information through different ISPs and email addresses will pay for the development of a preference center. For others, there’s no real value there. How much money are companies leaving on the table by not providing a mechanism for recipients to change their email address?