[K12OSN] Student email

[Jim Kronebusch]

I think a simple solution would be to setup a standard email server (any 
type of setup, I like Postfix with OpenWebmail).  Then decide what type of 
access you want.  I like webmail for offsite and clients for LAN access.  So 
for the Internet just don't setup any MX records, just a standard A record 
for webmail access and block all ports to the internal IP other than 80 
and/or 443.  Then on your internal DNS server you can setup standard MX 
records so that mail clients will work (unless you don't want them to).  
Then nobody from outside your LAN will be able to find the server for 
sending via SMTP.  Of course your users would still be able to send to other 
domains unless you block the server from sending via smtp at your firewall.

The following I think poses a better option: Postfix and other mail servers 
have settings where you can enter in allowed domains that users are able to 
send to.  With Posfix you can simply check a radio button through webmin to 
allow the domain to only recieve mail for the local machine only.  You can 
also easily enter allowed networks in Postfix for client access, only enter 
the local LAN and the only people who can access the server externally are 
those with a login for webmail.  You can also modify the relay_domains 
variable which controls what domains your users are allowed to relay to. A 
quick scroll through main.cf (Postfix main config file) will quickly help 
you understand what your options are.

Bottom line is Postfix gives you a ton of options for configuring who your 
users can send to.  If you would decide to go this way I have an excellent 
link for a tutorial on setting up Postfix+SquirrelMail+SpamAssassin+ClamAV 
(of course you wouldn't need SpamAssassin) on WBEL (should work easily for 
any other RedHat base distro like Fedora).

-- 
This message has been scanned for viruses and
dangerous content by the Cotter Technology 
Department, and is believed to be clean.