Final answer:
An anonymous remailer is a service used by internet users who want to remain anonymous by stripping the originating IP address from their emails.
Step-by-step explanation:
Internet users who wish to remain anonymous can send email through a anonymous remailer service. This type of service utilizes special software to remove or mask the sender's originating IP address, thereby maintaining the sender's anonymity online.
An ISP (Internet Service Provider) is the organization that provides Internet access to users, and it is not the service that would anonymize email. A John Doe is a term used in legal contexts for an anonymous or unknown person and is not related to email anonymity. Similarly, an Internet filter is typically used to block or restrict content on the web and it's not used for anonymizing communications.