Mail Transport Agents (MTA)
---------------------------
Postfix is a good choice as allround MTA: Robust, elegant configuration
logic, extreme scalability.

A pool of mail exchange (MX) backup servers is listed in the file
/etc/local-COMMON/postfix/permit_mx_backup_networks
(/etc/local-COMMON/postfix/mx_networks is deprecated!).

The script /etc/local-COMMON/postfix/anti-uce.sh started as an antispam
autoconfig script, but is evolving into a catch-all script for StartTLS,
MX backup pool, (maybe) pop-before-smtp and other tweaks.

Postfix 2.0.1 has just come out, with improved responses when emails are
blocked by RBLs: http://www.rfc-ignorant.org/how_to_domain.php

More about TLS in postfix: http://rr.sans.org/email/TLS.php

Read this about generally encrypting emails between MTAs whenever
possible: http://www.homeport.org/~adam/starttls.html

Mail Delivery Agents (MDA)
--------------------------
Here's a thread on optimally building a flexible auto-responder using
procmail (the post chosen gives the best result, but lacks explanation):
http://www.rosat.mpe-garching.mpg.de/mailing-lists/procmail/1999-09/msg00254.html

The script /usr/local/sbin/userforward adds (or optionally overwrites)
a .forward and forwards email cruft lying in the incoming spool.

The script is deliberately kept free from interactive dialogs to support
remote triggering from an email, sms or similar.

POP/IMAP daemons
----------------
UW IMAP and POP3 daemons are currently the best/easiest to integrate
with a heterogenous environment.

dovecot just arrived as Debian package is a promising alternative once
mature - it is ekstremely streamlined and delivers to ~/home by default.

Recent Debian packages are compiled with cleartext passwords turned off
by default. We are not quite ready yet for this move, so here's what
needs to be done to circumvent it: Create the file /etc/c-client.cf and
add the following lines:

I accept the risk for IMAP toolkit 4.1.
set disable-plaintext nil

(Remember the final dot in the first line! - even though I think they
have relaxed on that now and don't even need the correct version now).

hile you are at it, consider adding this one as well (but then make
sure that the ~/mail directory then always exists!):

set mail-subdirectory mail

The script /usr/local/sbin/user-init checks (among alot of other stuff)
for the existense of that directory - when enabled in the hint file
/etc/local/users.conf

Mail User Agents (MUA)
----------------------
/usr/local/bin/xpine and /usr/local/bin/xmutt fires up your favourite
low-tech MUA even in a hi-tech environment :-)

If debugging StartTLS and SASL avoid using Evolution: It leaves a small
daemon running possibly not freeing SASL from memory. Use the command
`lsof | grep sasl` to check if SASL is in use (is there a better way?).

------------
Here's a brief overview of interaction between mail agents and daemons:
http://lists.samba.org/pipermail/linux/1999-September/003605.html

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$Id: Email.txt,v 1.4 2003-01-02 00:57:54 jonas Exp $