OpenSMTPD is an implementation of the server-side SMTP protocol as defined by RFC 5321, with some additional standard extensions. Its design goals include security, reliability, ease of configuration, and support for common use cases.
It allows ordinary machines to exchange emails with other systems speaking the SMTP protocol.
smtpd can listen on a network interface and handle SMTP transactions; it can also be fed messages through the standard sendmail interface. It can relay messages through remote mail transfer agents or store them locally using either the mbox or maildir format. This implementation supports SMTP as defined by RFC 5321 as well as several extensions.
This is free and open source software.
Website: www.opensmtpd.org
Support: Manual Pages
Developer: The OpenBSD Project
License: ISC License
OpenSMTPD is written in C. Learn C with our recommended free books and free tutorials.
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