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.
Warmbox.ai - Warm up your cold email inbox, and never land in spam anymore!
Roundcube - Web-based IMAP email client
Warmup Inbox - Warmup Inbox is a tool that automates the process of warming up your email inboxes, raising your sender reputation and inbox health automatically.
iRedMail - A fully fledged, free email server solution, an open source project (GPL v2).
MailReach.co - The #1 email warming service to improve your deliverability by generating realistic and meaningful engagement to your emails. Easy-to-use solution to help you land in the main inbox instead of the spam folder.