I'm not sure if this will work on SME5.5. I expect it will but offer no guarantees!!!
If you have a test server running 5.5 and wish to give this try, please report your results.
1) From your closest mirror, download this rpm. Example:
http://www.ibiblio.org/pub/linux/distributions/e-smith/contrib/CharlieBrady/RPMS/i386/mailfront-0.86-1es2.i386.rpm
2) Use the server-manager to add a user named 'maillog'
3) Add the rpm:
# rpm -Uvh mailfront-0.86-1es2.i386.rpm
4) Add the environment variable:
# echo maillog > /var/service/smtpfront-qmail/env/LOG_RECIPIENT
5) Send some e-mails and you should find messages delivered to intended recipients plus archival copies in the 'maillog' inbox.
Darrell