Using date based mail archives to set up a RSS feed with cron in bash.
Create a rss directory in /var/www/ and copy these two files into it.
You will need to edit scripts and header to match your environment.
Be sure and set proper permissions on the file.  Once you have tested
the script (./var/www/rss/rss-feeder) successfully, add a bash script
to run this script hourly in cron.

Header file (./rss/header)
**************************
<?xml version="1.0"?>
<rss version="0.91">
<channel>
<title>My Feed Title</title>
<link>http://www.mysite.com</link>
<description></description>
<language>en-us</language>
<image>
<title>The Mailing List</title>
<url>http://www.mysite.com/graphics/logo.gif</url>
<link>http://www.mysite.com</link>
<width>130</width>
<height>30</height>
</image>

rss feed (./rss/rss-feeder)
***************************
#!/bin/bash
# Instant archive list RSS feed generator
# Run every hour, it extracts the latest subjects
# from the list archive and generates an RSS feed for
# the last 15.
#
# Troutman 20051011

# Variables
Lines=0;
wd="/var/www/rss";
year=`date +"%Y"`;
month=`date +"%m"`;
adir="/var/www/html/arch/$year/$month";

# If archive dir exists, get listing
if [ -d $adir ]
  then ls -t $adir > $wd/temp
  else exit 0;
fi

# Make an archive and start with fresh header
touch $wd/feed.rss
cp $wd/feed.rss $wd/feed.rss.old
cp $wd/header $wd/feed.rss

# Cycle through the directory and grab filenames
exec 3<> $wd/temp
while read subj <&3
do {

if [ $Lines -lt 15 ]
then
  echo "<item><title>$subj</title><link>" >> $wd/feed.rss
  echo "http://www.mysite.com/arch/$year/$month/$subj</link>" >> $wd/feed.rss
  echo "<description>$subj</description></item>" >> $wd/feed.rss
  (( Lines++ ));
fi
}
done

echo "</channel></rss>" >> $wd/feed.rss

cp $wd/feed.rss /var/www/html/

exit 0