If you are a developer, you can customize contact’s email and email configured in the system here: modules/mod_jaquickcontact/mod_jaquickcontact.php
$header = "From: $email";
$message = "
".JText::_('Name').": $name <br/>
".JText::_('Email').": $email <br/> ";
$message .= "<br/>" . nl2br($text);
$email_copy = (JRequest::getVar('email_copy', 0) == 1) ? 1 : 0;
$adminemail = $mainframe->getCfg('mailfrom');
$recipient = $params->get('recipient', $adminemail);
$recipient = preg_split("/*[,]*/", $recipient);
$mail = JFactory::getMailer();
$mail->addRecipient($recipient);
if ($params->get('show_email_copy', 0) && ($email_copy == 1)) {
$mail->addRecipient($email);
}
$mail->IsHTML(true);
$mail->setSender(array($email, $subject));
$mail->setSubject($subject);
$mail->setBody($message);
$success = $mail->Send();
check the red lines above.