Compare Postfix vs. Sendmail vs. qmail

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.

The Sentrion platform from sendmail is crafted for intricate and expansive environments, yet we also offer a portion of this solution as open-source. While Sentrion may not suit everyone’s needs, it is an excellent choice for those employing open-source email systems within large and complex infrastructures, as it can support your messaging strategy for the long term, encompassing aspects like virtualization, consolidation, and cloud migration. The Domain Keys Identified Mail (DKIM) standard plays a pivotal role in email security by allowing senders to digitally sign their messages, enabling recipients to verify that these messages are genuine and have not been tampered with. This sender authentication process ensures that recipients can trace the origin of an email back to the sender's domain, providing assurance regarding the integrity of the message content. Utilizing cryptography, DKIM offers a widely accepted solution for reducing email fraud, thereby safeguarding an organization's brand and reputation while keeping implementation costs manageable. With the increasing prevalence of email threats, adopting DKIM can be a crucial step in fortifying your email security framework.

qmail serves as a robust, secure, and efficient message transfer agent that prioritizes simplicity. Its emphasis on security is not merely an aspiration but a fundamental necessity, given the critical nature of mail delivery for users, which must remain uninterrupted and entirely secure. With a philosophy that ensures a message, once accepted, is never lost, qmail adopts a straight-paper-path approach to guarantee reliability. Additionally, it offers optional support for maildir, a highly reliable mailbox format that prevents corruption during system crashes—unlike traditional mbox files and mh folders. This feature allows users to read their emails safely over NFS, with the added advantage that multiple NFS clients can deliver emails concurrently. Notably, qmail's design is considerably more compact than other Internet MTAs, which often rely on separate mechanisms for forwarding, aliasing, and mailing lists; instead, qmail streamlines this with a singular forwarding system that empowers users to manage their own mailing lists efficiently. Ultimately, qmail stands out not just for its performance but also for its innovative approach to email management.