setting up a LAN mail server
 

I want a local, asynchronous communication system for me and a few (less than 20) friends, and I think that a LAN mail server is just what I need.

I'll give people IMAP, POP3, and webmail access from the outside (Internet) but I will only allow mail from, and to localhost. Noone will be able to send or recieve mail from Gmail, Yahoo, Hotmail, and the such.

Can you tell me what software I need, and a brief outline of the process? Just enough so I can start googling things.

I have a favorism for software carried by the standard Slackware distribution, so that the Slackware team can handle security updates. However, if the benefits are outstanding, I can start compiling software.

I'm running Slackware 13.37.

Dunno about slackware packages, but you'll need an SMTP server (postfix is probably the easiest to set up in a simple fashion, with excellent docs) and a POP3/IMAP4 server (dovecot for the same reasons).
For webmail access, anything that takes your fancy (squirrelmail, again is basic and easy), and of course a webserver to, well, serve it ... :)

Then why do you think this is helpful?

sendmail (for sending email) and procmail (for filtering incoming email) are standard.

You have a choice between fetchmail and getmail to receive mail (both are provided).

Slackware comes with a pop3 server (popa3d) as well as imapd.

There are additional things available at slackbuilds.org.

I cannot comment about webmail offerings.

Well that particular bit obviously isn't, but the rest is relevant to the question posed, and I thought it might be good to qualify my answer as not slackware specific (which, by the way, was not a hard dependency of the request).

That seems remarkably unhelpful as well... you probably shouldn't have bothered at all. :D

I setup my email server using postfix + dovecot (imap) + roundcube (webmail)
I also used postgrey for spam blocking

Here is a howto for salix OS, salix OS is distribution based on slackware closely. http://www.salixos.org/wiki/index.ph..._a_mail_server

Back in the day I used qmail for my local LAN mailserver (complete overkill as I only had 2-3 machines). Lots of documentation at:

www.qmail.org
cr.yp.to/qmail.html (the author's site)
www.lifewithqmail.org (a comprehensive guide to setting it up)