Halon MTA - Scriptable and scalable SMTP server and email framework designed for service providers.
PowerMTA - PowerMTA is an industrial-strength software for high-volume email delivery.
KumoMTA - KumoMTA is the world's first Open-Source MTA designed from the ground-up for large-volume senders. Get a fast, flexible, supported solution.
Postfix - Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
EmailSuccess - EmailSuccess is an advanced MTA built to handle the most critical reliability, performance, security, and deliverability requirements.
Amazon SES - Scale your business email & marketing messages with Amazon Simple Email Service (SES), a cost-effective and reliable cloud email service. Sign up today.