Core

I'd say it's a bug. And the bug itself is that the extension is using the FE rendering template also for the mail rendering. I also had this issue when I customized the form layout via TS (as far as it's possible with this limited templating "engine"). The only way to fix it for me was to XCLASS the form extension (class tx_form_View_Mail_Html) and overwrite the typoScript configuration passed to the constructor with email specific TS (if defined). Here is what I did in my XCLASS.

public function __construct(tx_form_Domain_Model_Form $model, array $typoscript) {
    // because the TypoScript Factory is singleton it currently holds the TS layout definitions
    // for the HTML form and not for mail output. Let's override this.
    $TsFactory = t3lib_div::makeInstance('tx_form_Domain_Factory_Typoscript'); // singleton
    if (isset($typoscript['email.']['html.']['layout.']) && count($typoscript['email.']['html.']['layout.'])) {
        $typoscript['layout.'] = $typoscript['email.']['html.']['layout.'];
    } else {
        $typoscript['layout.'] = array( 'foo' => 'bar'); // must not to be empty in order to overwrite the current settings, any values will work
    }
    $TsFactory->setLayoutHandler($typoscript);

    return parent::__construct($model, $typoscript);
}

Same happens for the confirmation view btw - but haven't figured out how to fix it there yet :(

I've added Patrick to the "watchers" list, maybe he could give us some insight and feedback on what he thinks of it.

Thanks for your report and your additional input, Franz!

Christian, so you are implying that this is not a bug? Maybe perhaps some feature that you might be missing?

Yes my particular issue was not a bug, but franz pointed out that there is a bug, since mailing and FE Rendering uses the same setup.

So the subject sould be changed to something like. "BE/FE rendering and mail rendering uses same setup" or even Better new bugreport should be created (Franz?).

Thanks for your patience and your help,

Christian.