DocuSign Admins may update email addresses for users using the bulk update procedure only if the organization has claimed the domain.
If you know that your organization has claimed the domain in question, then you can download and populate the CSV template for updating users. The UserEmail column will remain unchanged and should contain the current user's email address. In the UpdatedUserEmail column, enter the new email address you'd like to use. After completing the import, the user's email address is updated.
If the domain has not been claimed, Admins can not change an email address for a user unless the Admin has first closed that user and then reactivated them on the new email address, which would indeed send a new activation link to the user and prompt them to create a new password. The users envelopes would still be inside after reactivation. I might advise trying this procedure on one or a couple individual users before closing and reactivating a large number of them.