Postmark is an email delivery service that offers reliable and fast email delivery, with a focus on transactional emails. It has a straightforward pricing model and transparent customer support. The company was acquired by ActiveCampaign in 2022 and has a strong reputation among its customers. Postmark's competitors include Mailgun, Amazon SES, and MessageBird, each with their own strengths and weaknesses. While Postmark is not the cheapest option, it offers a high level of quality and reliability, making it a good choice for businesses that require a stable email delivery service.