Ok, so now we have a hardened server in play, the next step is to find some collaboration-ware to put on it. To my mind, there are several options, and there are also a couple of different purposes that I am trying to fulfill.
Private CloudFor this purpose, my decision is already made. I've been playing with ownCloud for some time, and I do like it. It is simplistic. Its uses extend beyond just a file share in a cloud. There is options for tracking tasks and sharing other information.
Private Email ServerEmail servers have been a challenge. In this field I have found three options; Citadel, Xmail and Exim.
I have watched Citadel mature over the last while (even had it running on a box for a while), and it seems to be coming together quite nicely, and from what I can read in their online instructions, setting it up should be reasonably straight forward - it comes as one install package. It has a nice clear UI, and it handles lots of different email/calendar tools. It also integrates with other email servers. Nice.
Xmail on the other hand, at first glance does not appear as such a good option. It is down-loadable as source - that's not too much of an issue. However, there are so many third party components, and the basic configuration information and details are so vast, from the short skim-read I've had, it feels like I'd need to a complete degree to wrap my head around it properly. Also, the most recent release of Xmail was 4 years ago. In the longer run I think Xmail could be more powerful, but given that I want this collaborative functionality up and running soon, Xmail is not my first choice. Citadel, I have installed and set up before, and I know it will be quicker.
Exim I have only just found. At this stage I do not know enough about it, and their web pages seem to have too little information up front, and possibly too many links to buy the book about Exim. Although it does seem to be a single install package like Citadel, which is good, it is something that I'd like more information to be readily available before I commit to it.