The best free alternative to Google Workspace is ONLYOFFICE, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Google Workspace and 15 is free so hopefully you can find a suitable replacement. Other interesting free alternatives to Google Workspace are Mailo (Freemium), Zimbra Collaboration Suite (Freemium, Open Source), Shelf.io (Freemium) and WikiSuite (Free, Open Source).
The Mercury Mail Transport System is a mail server that sends and receives messages on behalf of a group of users on a machine or local area network. Messages from the outside world are received by Mercury and delivered to the users, who can access it at any later point.
Virtual Office, Online Office, Digital Learning Space, Online Groupware - ContactOffice, Keep a virtual office on the web. Share documents, contacts, calendar, tasks, ... with clients, students, suppliers, friends or family.