Trying to figure out a good mail setup

Question

I'm connected to a campus network.  My setup consists of a slow but functional desktop which I'm using as sort of a "server" with important applications screened, and a fast laptop which I use for general purposes, move around, and access the desktop's screen sessions from.  (The desktop also has lighttpd/php/mysql/vsftpd running, etc).  I also have another desktop that I may be setting up soon.
I would like to have some kind of central mail system.  On both laptop and desktop I currently have postfix setup for host only mail, but I was wondering if there's an easy way to have sort of a "central" mailbox.  I.e., I want a simple mbox style mailbox that I can somehow share between the two, or maybe just a way to send simple mail from one computer to the other, but not through my school's SMTP/IMAP.  I don't think I need a full-blown IMAP or POP setup, I just want to be able to easily send messages between the two computers.  I'm not very experienced with the linux mailing setups, so can someone just point me in the direction of a setup that might work?
I have been reading the wiki and googling, but most guides seem to either focus on local only mail, or sort of a small business network setup, whereas I want something in between.  I realize I'm not being terribly clear, but I'm sort of flexible in the setup as long as it works.

Answer 1

Ok, here they are.  This is a brute-force method for creating a local email server behind a firewall; nothing goes out on the net. 
I'm sure there's a more elegant way of doing this, but with my limited understanding of the protocols involved, I plowed through it and got this to work.  The setup is almost certainly unsecure on the net.
The setup:  A machine named machine1.me.local (so named in rc.conf) running archlinux.  I tried using a shortname like machine1 without the rest, I couldn't get it to work. I share files on a workgroup using samba, so I don't have a DNS server or domain set up on my network. The user name is normaluser.
1.  Make backup copies of every file you're going to change, so you can restore them if you mess up; e.g.
main.cf.backup
2.  Get postfix and courier-imap using pacman:
pacman -S postfix courier-imap
3.  As root, edit /etc/postfix/main.cf, uncommenting the following lines:
#myorigin = $mydomain
#mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
#home_mailbox = Maildir/
4.  Go to /var/authlib/authdaemonrc and edit the authdaemonlist line to:
authmodulelist = "authshadow"
5.  Go to /etc/postfix/aliases and uncomment the line:
#root:        you
and replace you with normaluser
6.  Go to the line that says #Put your local aliases here.  Under that, put the line:
normaluser:    normaluser
(I suspect this last may not be necessary, but I didn't take time to test it again without that change)
7.  At the command prompt, type:
newaliases
8.  Go to /etc/hosts.allow and add a line:
portmap: localhost 127.0.
9.  Become normaluser and go to /home/normaluser.  Type:
maildirmake Maildir
(if you are going to have more than a couple users, you may want to do something like this in skel, so you can just copy it across to their user home directories.  This step has to be done for every user who will have an email account.  There's a way to set up virtual users, but I didn't get into that.)
10.  Add the daemons into rc.conf after network:
postfix portmap fam authdaemond courier-imap
11.  Restart your server.  If luck is with you, you should be able to set up an email account in thunderbird or the like for [email protected], and send and receive mail.  Your outgoing and incoming server need to be set to machine1.me.local.
When problems arise, /var/log/mail.log can be helpful.  Let me know if it works for you.