Postfix might be a bit more popular than Sidemail. We know about 1 link to it since March 2021 and only 1 link to Sidemail. 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.
Sidemail is an all-in-one email delivery service mainly focusing on SaaS businesses. It’s built upon Amazon's robust architecture in combination with custom in-house configurations that ensure highly reliable and scalable email delivery. - Source: dev.to / 25 days ago
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
Mailook - Identify & fix your email deliverability issues for free 👀
iRedMail - A fully fledged, free email server solution, an open source project (GPL v2).
Postal - Open source mail delivery platform, alternative to Mailgun or Sendgrid
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.
Mailivery - Reach the Inbox, not the spam folder.
Exim - Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.