Hello,

I am looking for a preferably free, web-based tool to manage user
accounts, mail aliases, ‘out-of-office’ messages, and reset passwords.

The problem:  I am looking for an EASY way for an office manager to
administrate users of a RedHat Linux 7.3 Sendmail server, other
solutions will be considered - not shell admin though :)

Thanks!

You should look at Webmin:

http://www.webmin.com/webmin/

For web based administration, webmin is a wonderful tool with very
easy to understand interfaces. Install the webmin tool on your server
and connect to the port 10000.  It allows complete sendmail
administration and also change passwords option.

For out of office messaging use the tool nwebmail. Check the site :
http://sourceforge.net/projects/nwebmail/ for downloads.

Another option for server administration is linuxconf which mostly
comes with Red Hat. However, refrain from using linuxconf for sendmail
administration, in case the version of sendmail is not supported on
the linuxconf.

Regards,
Subhasis