This is a mail server. There are two versions. First one is for 5 users MAX and the other for more. While you can start with the free 5 user version, as your business grows, you can graduate to the larger version.
MDaemon FREE mail server software is a 5-user license version of the MDaemon Email Server for Windows. MDaemon FREE suits the SOHO segment quite well. There is no need for any investment initially until your usage grows beyond 5 users. The mail server is compatible with SMTP and POP3 protocols for Windows Vista/XP/2008/2003/2000 systems. The software also provides for Internet based e-mail access from anywhere through the WorldClient functionality. These features let users access and manage email, address books, and calendars remotely through their web browser. It also has spell check, shared calendaring and scheduling, multiple language support, email account creation, and customizable themes etc.
The software provides remote administration and powerful content filter to guard against Spam. The interface is available in multiple languages that include English, German, French, Spanish, Russian, Japanese, Portuguese, Italian, and Chinese.
Features offered include email authentication and certification, security features, an easy to use group-ware. The Outlook connector lets the collaborative functions of Microsoft Outlook to be used with MDaemon as the mail server and group-ware platform. Outlook users can share Calendar, Task, Contact, Notes, and Journal folders without the expense or expertise required by Microsoft Exchange Server. Remote administration allows administrators to securely manage MDaemon, Fax, and WorldClient from anywhere. Backups and restoration is easy. An easy to use server if you communication needs are not so complicated as to need complex solutions like the MS Exchange.