When you are viewing an emailed newsletter, there is a link to "change your email preferences" on the emails. On my account it goes to http://stackexchange.com/users/101122/jessica-brown?tab=subscriptions
I would like to propose making this page more useful by adding a link to the page where you can update the email address for newsletter subscriptions. You can already do this for filters, why not for newsletters too?
From https://stackoverflow.com/users/preferences/272208 I can update my notification address, but is this where all newsletters go, or only stackoverflow's newsletter? It's not so clear from the URL (though actually updating my address there did appear to affect other network sites)