Change outgoing email to user profile.

The outgoing email is one address for the whole site. Most of my sites need the email to be the user's email address. I made the following change to compose. It should be some sort of config option.

From:

$mail->Username   = $_webmail_plus_config->smtp_username;
$mail->Password   = $_webmail_plus_config->smtp_password;

To:

$mail_api_server_info = mail_api_server_configuration($_webmail_plus_config->domain);
$mail->Username   = $user->name . $mail_api_server_info->login_suffix;
$mail->Password   = _webmail_plus_get_user_password($user);