Mail Users
This is pretty simple and straight forward form that the admin can use to send an email to a registered user, or all registered users, from the drop down list or by checking "mail all registered users".
Simply select a registered user, or check "mail all registered users", put in your email address in the "From" line, put in the email address you want replies to go to into the "Reply-to-address" line, type in a subject and the body of your message and click "Send mail".
This tool is handly to contact each registered user to inform them of site updates, downtime, or just about anything you would like.