Best MTA Products in 2025

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

Key Postfix features:

Security Performance Compatibility Reliability

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. .

Key MailReach.co features:

Deliverability Improving Email Warming Meaningful Warming Content Smart Warming Algorithm

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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

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

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

Key CMail features:

User Interface Security Features Integration Customization

free

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

MailerQ is a high performance Mail Transfer Agent (MTA) designed for delivering large volume email messages at very high speeds.

Key MailerQ features:

High Performance Flexible Configuration Scalability Real-time Monitoring

msmtp is an SMTP client.

Key msmtp features:

Lightweight Configurable Scriptable SMTP Server Support

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

esmtp is a user configurable relay-only Mail Transfer Agent (MTA) with a sendmail compatible syntax.

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

Configure SMTP e-mail in IIS when you want to deliver e-mail messages from your site.

Key Microsoft SMTP Server features:

Integration with Windows Server Simplicity Cost-effective Security Features

Development, Network & Admin, and Office & Productivity.