Based on our record, Postfix seems to be more popular. It has been mentiond 1 time since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
Read the documentation on postfix.org and/or buy one of the many available Postfix books (it really helps to understand the Postfix philosophy). Source: about 3 years ago
mailcow - An open source mailserver suite.
iRedMail - A fully fledged, free email server solution, an open source project (GPL v2).
Modoboa - Modoboa is a mail hosting and management platform including a modern and simplified Web User Interface.
Zimbra - 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.
Mail-in-a-box - 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.
Exim - Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.