I have very little experience hosting my own server. I have been using a VPS for all of my needs. However I am now setting up a small company site and e-mail system, and it is all hosted on the VPS. However the company, although small, does alot of business with large corporations and government, so I need to ensure that e-mails don't get lost or bounced. As such I just got approved to purchase a computer to use as a secondary MX/SMTP/nameserver for the site (with about 30 e-mail accounts). Maybe also as a database back up, but thats down the road.
We are running on a company LAN with no hosted servers and I'm almost positive I can't use a NASD (or wouldn't want to) as any kind of server. That's pretty much all I know at this point. Here's what I want to know
What would be a good, yet basic and affordable, system for these needs? Where would you recommend I get it from?
If my VPS base server is UNIX, would I need to purchase a UNIX machine?
If I set it up with a static IP, will I be able to add that IP into the Plesk running on my VPS? (doubtful probably)
How difficult would it be to set up as a MX/nameserver? Can it be setup using apache (or similar)?
If I can't set it up with a static IP, do I have to use some sort of dynamic DNS service?
Edit:NDAS, not NASD