Reliable email relay, API, and delivery service SMTP has been a leader in email relay services for over 20 years. The brand is synonymous with the technology that facilitates the internet鈥檚 email engine. SMTP is the solution that powers transactional emails for thousands of the world鈥檚 leading brands. SMTP鈥檚 relay services help build a better IP reputation, optimize inbox placement rates and ensure messages reach your subscribers. Search Job Openings 5K annual users5,000 annual users11B emails sent11 billion emails sent annually5,000/s sending velocity5,000 emails per second sending velocity