From Elcom Soft:
Advanced Direct Remailer is a remailer which sends your message straight out to the recipient's mail server. ADR realizes multi-threaded direct delivery, and so works several times quicker than usual email client. The program has its own internal SMTP server, and can be easily integrated into any email client. Open API for developers (plugins, COM or ActiveX interfaces, samples, and sources). Support for mailing lists, databases, and Socks5.