[NTLUG:Discuss] Mail, IMAP, sendmail, fetchmail

[Kelledin]

On Saturday 17 August 2002 03:53 pm, nf0 wrote:
> After attending today's meeting, I've decided that I want to
> setup an IMAP mail server at home, and use sendmail and
> fetchmail. I've never gotten into this site of things on Linux
> before. I've look through the docs and have looked online with
> little help on getting this going. Does anybody have any good
> links or information they would like to share so I can kick
> off this project. I've already gotten all there installed, its
> configuring them that's somewhat confusing.

First it's necessary to understand what all the stuff you want 
does.  Some of this stuff may have been covered at the LUG 
meeting; sorry if I'm being redundant, as I wasn't able to 
attend. =(

sendmail functions as an SMTP server; it sits and waits for mail 
to come in, and when it receives mail, it hands it off to a 
specified delivery agent like procmail or cyrus.  When commanded 
to do so, it will send messages to other machines via SMTP, or 
to users on the local machine via local mailers.

fetchmail functions as a polling mail retrieval service.  It hits 
up a specified POP/IMAP server every few minutes, downloads any 
new messages, and hands them to a local sendmail service.  
sendmail then takes care of delivery to appropriate local users.

procmail functions as a mail routing/filtering program; on a home 
system, sendmail is typically configured to hand mail to 
procmail or something similar for routing to user-specific 
mailboxes on the local machine.

POP/IMAP servers (such as wu-imapd, courier, or cyrus) maintain a 
mail storage database and allow users to download their mail 
from remote locations via POP or IMAP protocols.  It's usually 
not necessary or even essential for you to run such a server, 
unless you want a mail hub for a local network.

SquirrelMail and other programs provide webmail interfaces for 
underlying POP/IMAP services--basically, they give you something 
like Hotmail's browser-based interface.  They're generally not 
necessary unless you're providing many users with remote mail 
access, and not all those users can set up an appropriate mail 
client like Outlook or Evolution.

It should be noted that there are alternatives for the above 
programs.  Instead of sendmail, I would advise you to use 
postfix; postfix performs rather better and is far easier to 
configure than sendmail.  sendmail is well-aged and quite 
mature, and it deserves some respect, but it's definitely not 
the fastest or leanest MTA around.

Here are some nice guides I've found for setting up sendmail on 
home systems:

http://hints.linuxfromscratch.org/hints/sendmail.txt
http://hints.linuxfromscratch.org/hints/postfix_fetchmail_procmail.txt

You typically don't have to compile from source as the above 
hints suggest (most distros will provide sufficient precompiled 
packages), but they contain some pretty good info on configuring 
mail after compiling/installing.  You can also check the HOWTOs 
and mini-HOWTOs on http://www.tldp.org/ , though I've found them 
to be somewhat lacking in the area of mail setup...

-- 
Kelledin
"If a server crashes in a server farm and no one pings it, does 
it still cost four figures to fix?"