Confirm addresses, product preferences and other information using online surveys from self-qualified visitors to their PURLs.
Pre-populate fields with the information already in your records to increase the ease and likelihood of a response. Offer an incentive to further boost response rates; this is particularly effective if information is needed to fulfill a request (such as confirming a shipping address for a gift or other requested item).
In our experience, the accuracy of our mailing list, as measured by undeliverable mail, was twice halved using PURL survey forms.