An inactive newsletter subscriber is an individual who has previously signed up to receive updates and information from a company or organization through a newsletter, but has not engaged with the content for a significant period of time. This lack of engagement can be due to a variety of reasons, such as losing interest, changing email addresses, or simply forgetting about the subscription. Inactive newsletter subscribers may still receive the newsletter, but their lack of interaction indicates a decreased level of interest or involvement with the company or organization.