Related Question:
Intranet Messaging
Is there some way that I can set up an email system inside my intranet here in my house. There are between 4 and 7 computers on at any time, It would be nice to have either an email or messenger system that we can use inside our secured network.
For something used just inside the house, your best bet is probably a Jabber server like OpenFire http://www.downloadsquad.com/2008/12/31/openfire-cross-platform-jabber-server/
If you want it to communicate with the outside world (Google Talk/ email), then more work is required, but you can still do it.
Quite frankly, as lazy as it sounds, in my house we pretty much just use normal email or MSN when we need to get something to each other. That being said, in answer to your question -
If Windows - I have previously used both HmailServer and Mail Enable Standard
I would highly recommend both, but if you want to use IMAP, then you really want to use HmailServer unless you wan to pay....
...Basically, I used Mail Enable Standard all the time but then I moved over to Hmail - Hmail has more features for free than the free edition of Mail Enable, however any of the pay editions of Mail Enable beat Hmail. That being said, you really don't need any premium features for your needs.
Just set up each pc the internal IP (or DNS) of the system running Hmail and away you go! You can have it set up in less than 2 minutes!
If using Linux / want to set up a VM, I cannot recommend and distribution over any others, but the easiest thing you can do is install Webmin and then you can install any of the many free mail programs (such as SendMail) and administer it all from a web GUI
Sure! There are a multitude of free SMTP servers available. Just google "free smtp server" or something. Or, if you prefer something more "complete" the free edition (limited to 10 users, single domain) of Smarter Mail is here: http://www.smartertools.com/SmarterMail/Free-Windows-Mail-Server.aspx
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I would go with ejabberd Jabber server.
In addition to setting-up a Jabber server, you could also look at installing an IRC server on your network.
I think the main issue that you'll face with any of these solutions, though, is that that machine has to be on for the others to communicate to it. Whereas, if you just use your "normal" email/chat/etc, then you can rely on it being available because the company that provides the service has to have their servers up or they lose money :)
Check out Google Apps for Teams or Google for Business
Chat, collaboration, and email included.
