Often subscribers opt-out, unsubscribe, or eventually bounce simply because they had no means of updating their new email address. A simple solution is to add an option at the footer of your emails, preferably close to the unsubscribe option, where they can chose to modify their contact details. This can have two other strong benefits. First, if you have multiple email lists you may be able to save them from unsubscribing fully by giving them the option to pick which lists they stay on. Second, you may be able to gather additional data points about them and add them to new lists. This can help future list segmentation efforts.
In Interspire Email Marketer it can sometimes be a little confusing to create and add a Modify Details form/page. This is because the email marketing software was designed for power users who want control and options and thus there is now simple push button solution for adding this option to your email campaigns. Instead you must, via the “forms” menu, create the modify details forms for each of your contact lists or groups of contact lists.
Here is a short video that walks you through the process from beginning to end.