This facility allows you to add a contact form to your web page, for example on a "Contact Us" type page. This allows the end-user to contact you by email, without you giving out your email address, thus lessening the chance of automated spam attacks.
Note that the editor used for the acknowledgement message is the tinyMCE editor. For a full description see: Edit Text Element.
The user id. of the user who is to receive the customer's message has to be given. Note that this is a 'auto-suggest' field, a bit like for Google search, in that when you have typed the first few characters of the user id. the system lists all users beginning with those characters. Click on the user id. you require.