In his latest Email Insider column, Loren McDonald recommends these best practices to get more subscribers to change their addresses instead of letting the relationship wither away:

• Call out the change of address explicitly. Label a text link high up in your message body as “Update Preferences/Email Address” or “Change Email Address.” If subscribers can change their addresses only by unsubscribing and then resubscribing, explain that clearly.
• Link directly to the profile or preference page.
• If your email technology enables it, pre-populate the Web site form with the current email address.
• Remove as many barriers as possible. Subscribers often either forget or don’t want to take the time to look up their log-ins or passwords, so make sure your password-recovery system delivers the info fast to their email.
• At minimum, put the change-of-address/preference-update link in an administrative or footer area in the message.
• Send a confirmation email to the new address to make sure it was entered correctly, and to confirm any other details the subscriber might have changed.
• Acknowledge the change immediately. Post a thank-you page or send a confirmation email. If you can, include a link to a discount, whitepaper download or other relevant incentive.

Source: Email Insider