Systems Administration & Troubleshooting
Docman is extremely easy to use for both the administrator and the end user. Users can easily view and download files from your website. jComments is an elegant comment solution. jComments is pretty to look at and works seamlessly with your Joomla website. XIJC is a site wide captcha program. XIJC is able to institute captcha on every user input field on your site. In order to fight spam this is a must have Joomla component.
This has got to be one of the best email programs in Joomla. Acajoom is a capable auto responder program. You are able to set up unlimited newsletters, auto responders and smart newsletters that automatically go out to your users. The next component is Acymailing. This Joomla component is similar to Acajoom. Acymailing has a wealth of features, it is an excellent email and auto responder program capable of anything you can throw at it. Between Acajoom and Acymailing it is a tie and a matter of preference because they both do and perform the same way.
"Essential Joomla Components Part 1"