Yes it could be!
NethServer can full manage e-mail, calendars, tasks, address books as well as an MS Exchange server.
Just keep in mind one thing: MS Exchange server has its native client MS Outlook to take advantage off all features, NethServer needs Mozilla Thunderbird to do the same.
Calendars, tasks and address books in NethServer are managed by SOGo, users can use them in two ways:
- trough SOGo Web UI
- by installing SOGo extensions for Mozilla Thunderbird
NethServer with SOGo enabled allows small-medium size companies replacing old MS Exchange installations or creating a brand new client-server communication/collaboration system.