In your administration control panel you can customize the e-mails that are automatically sent out. Start by clicking Customize Emails.
A list of current system e-mails is given to you, such as the e-mail that is sent out when a new ticket is submitted. Click on the name of a message to edit it.
You can edit the "From" line of the e-mail, the subject, and the body of the e-mail. The body of the e-mail can contain shortcuts such as %name% and %id% which will be automatically replaced with the user's name and the ticket's ID number, respectively. When you are finished, click Update.
