Based on our record, SOGo 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.
Episode 3, which I will bookmark as it lists the solutions that they have selected. I read e.g. About SOGo and Zorin OS that I didn't know of. Source: about 1 year ago
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.
Roundcube - Web-based IMAP email client
iRedMail - A fully fledged, free email server solution, an open source project (GPL v2).
Rainloop - RainLoop is a web based email client.
Exchange - On-demand technical interview coaching by engineers
Axigen - Axigen is an integrated email, calendaring & collaboration platform, built on a Linux mail server technology.