OpenSMTPD
OpenSMTPD is a FREE implementation of the server-side SMTP protocol as defined by RFC 5321, with...
Some of the top features or benefits of OpenSMTPD are: Simplicity, Security-focused, Lightweight, Integration with OpenBSD, and Active Community. You can visit the info page to learn more.
- Open Source
Best OpenSMTPD Alternatives & Competitors in 2025
The best OpenSMTPD alternatives based on verified products, community votes, reviews and other factors.
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Open-Source Alternatives.
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Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
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sSMTP is a simple MTA to deliver mail from a computer to a mail server.
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The #1 email warming service to improve your deliverability by generating realistic and meaningful engagement to your emails. Easy-to-use solution to help you land in the main inbox instead of the spam folder.
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Sendmail is a general purpose internetwork email routing facility that supports many kinds of...
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Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.
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msmtp is an SMTP client.
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Microsoft Exchange Server is a messaging and collaborative software product developed by Microsoft.
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sendEmail is a lightweight, command line SMTP email client.
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Zimbra is trusted by over 500 million users to increase productivity with a complete set of collaboration tools while maintaining total control over security and privacy.
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A fully fledged, free email server solution, an open source project (GPL v2).
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Blat is a small, efficent SMTP command line mailer for Windows.
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mailsend-go is a command line tool to send mail via SMTP protocol, written with golang.
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A small Mail Transport Agent (MTA), designed for home and office use. Part of ...
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CMail is a free Windows command line mailer with advanced message formatting options.
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