Navigate to the Control Panel > People Tab > Website Modules > Volunteering>Configure>Email Reminders
Configuring Reminders
Click Options - Email Reminders.
Click the Edit icon to edit the standard text of the email. For more information on editing System Emails, see Customizing System Emails.
Sending Reminders
Reminders are sent to volunteers automatically based on the timing defined in the opportunity's settings, in addition to a confirmation email when they sign up.