Halon MTA
Scriptable and scalable SMTP server and email framework designed for service providers.
3 Alternatives To Halon MTA
EmailSuccess
EmailSuccess is an advanced MTA built to handle the most critical reliability, performance, security, and deliverability requirements.
Exim
Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.
PowerMTA
PowerMTA is an industrial-strength software for high-volume email delivery.