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
Roundcube - Web-based IMAP email client
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.
Mailo - Mailo is an email client where you can send and receive emails to and from anyone with an email address.
Rainloop - RainLoop is a web based email client.
Mailpile - Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.
iRedMail - A fully fledged, free email server solution, an open source project (GPL v2).