Best SMTP Services for Linux of 2025

Reliable cloud-based email hosting includes features such as spam filtering, antivirus protection, ample storage, and webmail access. It seamlessly integrates with Outlook as well as various other POP3/IMAP clients. For users with high sending needs, it offers a robust SMTP service designed for responsible senders. Additionally, there is an outbound relay service tailored for transactional emails, marketing campaigns, newsletters, and diverse applications. The infrastructure supports dedicated email servers, clustering, and multiple IP load balancing to accommodate high-volume senders effectively. With a fixed monthly fee, users benefit from unlimited sending capabilities and reputation monitoring. Greatmail stands out as an email service provider (ESP) focused on delivering business-class email hosting, SMTP hosting, and specialized email servers. Furthermore, for ISPs, software developers, and cloud architects, we also create custom solutions featuring dedicated IP servers and load-balanced configurations with multiple servers to meet specific processing needs. This commitment to adaptability ensures that all clients receive the best possible service, tailored to their unique requirements.

Reliable SMTP relay services and email delivery services. You can send and track large volumes of emails with ease using powerful email delivery services. In minutes, integrate and you can start sending. All your email delivery, transactional and email relay needs are covered under one roof. SMTP can deliver whether you need a reliable backend solution or scalable infrastructure to handle large volumes of emails. Reputation Defender, SMTP's proprietary technology, uses big data to proactively monitor and protect your email list health. It also suppresses bad emails from soft and hard bounces in order to protect your IP reputation and domain. This will ensure that your delivery rates and inbox placement gradually improve over time.

Postfix is a mail server developed by Wietse Venema, originally created at IBM research as a viable alternative to the popular Sendmail program, and Wietse continues to enhance and maintain it while working at Google. This robust mail server operates on various UNIX systems including AIX, BSD, HP-UX, IRIX, LINUX, MacOS X, Solaris, and Tru64 UNIX, requiring ANSI C, a POSIX.1 library, and BSD sockets for its functionality. Designed with speed, ease of administration, and security in mind, Postfix features an exterior reminiscent of Sendmail, yet its internal architecture is entirely distinct. Among its key capabilities are the support for multiple SMTP deliveries over a single TLS-encrypted connection, leveraging the existing tlsproxy(8) and scache(8) services, as well as the ability to utilize MySQL stored procedures. Moreover, Postfix implements a gradual degradation feature, allowing a daemon to log warnings and continue operation despite encountering some service issues, rather than terminating abruptly with a fatal error. Additionally, it can set the execute bit on a queue file, which is critical, as failure to do so would prevent any mail from being delivered successfully. This combination of features makes Postfix a versatile choice for mail server management.

EmailSuccess provides high volume email sending with enterprise-level SMTP Servers. EmailSuccess can be used as a Mail Transfer Agent (MTA) for all sizes of senders: ESPs and Marketing Automation Companies. High Performance EmailSuccess, an MTA, is designed to deliver large volumes of email. It gives the business full control over the Speed, Latency and Deliverability parameters. Deliverability Clients must be able to deliver their messages quickly. You must ensure that your email is not blocked by spam filters and lands in your inbox. Advanced Sending Intelligence Optimized delivery through automatic and real-time tuning of email delivery parameters; platform tuning is made easy.

Exim serves as a mail transfer agent (MTA) for Unix-like operating systems. Initially developed by Philip Hazel in 1995 for the University of Cambridge Computing Service's email systems, Exim is released under the GPL, allowing users to freely download, utilize, and modify it. While it shares some similarities with Smail 3, Exim has evolved to offer greater user-friendliness and flexibility. Both Exim and Smail 3 operate on the Sendmail design model, where a single main binary manages all MTA functionalities. Although this monolithic architecture is sometimes viewed as less secure and slower, Exim boasts a superior security record compared to Sendmail and matches the performance of Qmail and Postfix, particularly in advanced functions like queue management, address routing, and testing. Notably, Exim lacks a built-in Graphical User Interface (GUI) for configuration, although some Linux distributions may provide one, enhancing its accessibility for users who prefer a visual approach. As a result, Exim remains a versatile choice for those looking to manage email systems effectively.

Codermails is an email application created by Coder technologies, renowned for its excellence in email marketing. This versatile software is ideal for sending newsletters, promotional content, welcome messages, product updates, and more. Compatible with both Windows and Linux operating systems, it also features built-in statistics for open rates and click rates, allowing users to track their engagement effectively. Additionally, Codermails offers a user-friendly interface that simplifies the email marketing process for businesses of all sizes.