Best SMTP Servers in 2026

Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.

Key Postfix features:

Security Performance Compatibility Reliability

Turn your inbox into a kanban board.

Key Kanmail features:

Unified Inbox Kanban Style Organisation Cross-platform Availability Privacy Focus

Try for free Open Source paid Free Trial $49.0 / One-off (Lifetime v2 license)

Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.

Key Exim features:

Highly Configurable Flexible Routing Active Community Support Efficient Transport Mechanism

Open Source

Sendmail is a general purpose internetwork email routing facility that supports many kinds of...

Key Sendmail features:

Established Reputation Highly Configurable Open Source Wide Compatibility

Mail-in-a-Box provides webmail and an IMAP/SMTP server for use with mobile devices and desktop mail software and also includes contacts and calendar synchronization.

Key Mail-in-a-box features:

Ease of Setup Full Control Cost-effective Open Source

Open Source

sSMTP is a simple MTA to deliver mail from a computer to a mail server.

Key sSMTP features:

Lightweight Easy Configuration Secure Email Sending Simplified Use Case

qmail is the name of an advanced level of mail transfer agent for the UNIX based operating systems.

Key qmail features:

Security Performance Reliability Modular Design

Blat is a small, efficent SMTP command line mailer for Windows.

Key blat features:

Lightweight Software Command Line Based Free and Open Source SMTP Integration

Open source SMTP server written in Node.js.

Key Haraka features:

High Performance Plugin Architecture Open Source Asynchronous and Event-Driven

Open Source

OpenSMTPD is a FREE implementation of the server-side SMTP protocol as defined by RFC 5321, with...

Key OpenSMTPD features:

Simplicity Security-focused Lightweight Integration with OpenBSD

Open Source

hMailServer is a free e-mail server for Microsoft Windows.

Key hMail Server features:

Free and Open Source Cross-Platform Compatibility Wide Protocol Support Built-in Anti-Spam and Anti-Virus

CMail is a free Windows command line mailer with advanced message formatting options.

Key CMail features:

User Interface Security Features Integration Customization

free

Brings voice and messaging to your web and mobile applications.

Key Twilio features:

Scalability Ease of Integration Global Reach Feature-Rich Platform

Open Source

mailsend-go is a command line tool to send mail via SMTP protocol, written with golang.

Key mailsend-go features:

Cross-Platform Support Simple Command-Line Interface Support for Multiple Protocols Attachment Support