According to this MediaPost article by Loren McDonald, email marketers should expect to lose at least 1/3 to 1/2 of your subscriber list every year due to list churn. A lot of that list churn comes from people changing their email address (like when they quit or change jobs, or just want a cooler email addy). Think about it. How many new email addresses have you created in the past 12 months?
So it’s probably important to have a link in your email that allows your subscribers to "Update Email Address" or "Update My Preferences."
If you’re a MailChimp user, you betcha that’s an easy thing to, and it’s already built-in to your account. Just add the *|UPDATE_PROFILE|* tag to your footer, and we’ll do the rest.