What is the difference between an ISP and an ESP?
- An ISP (Internet Service Provider) sends and receives E-Mail on behalf of their customers. Mail from an ISP is commonly expected to be 1:1 and human-to-human communication. ISPs typically provide more than just E-Mail services.
- An ESP (Email Service Provider) mainly sends E-Mail on behalf of its customers. Mail from an ESP is expected to be commercial in nature, optionally comes in large bulks and is machine-to-human communication.