I work in a small office with about 35 people and we are all on a intranet. This network is not connected to the internet.
Is it possible to set up an email server, with which we could send emails to each other ( we don't need to send emails outside our network).
I cannot use a messenger service like Openfire, since the messages could be asynchronous and we'll like to get those emails in a email client like thunderbird.
Another obstacle we have, is that we do not have a domain name.
Any ideas on which free (as in beer) software could be used? we have both windows and linux machines.