Setting up "Out of Office" autoreply on linux mail server
Solution 1:
There's a program called vacation that is a part of most unix and linux distributions. It is server based, and you can set your own messages. I don't think it's too smart, though, so it might not support the first two point on your list.
Solution 2:
- Postfix Add-on Software | postfix.org
- Autoresponders to accompany Virtual Users and Domains with Postfix, Courier and MySQL | howtoforge.com