[TYPO3] mailformplus: adding extra fields and sending multipart/mixed mail

[Claudio Strizzolo]

Hi all
I have two questions about the Mailformplus (th_mailformplus) extension:

1. After the form was submitted by the user, I need to add some extra
   fields according to some fields the user put in.
   A (stupid) example: the user can select an item through a dropdown
   box:

        Choose your favourite fruit: banana
                                     apple
                                     orange

   Now, I need to send to the mailform target both the fruit supplied
   by the user, and its color that I can automatically get from a
   database, a text file or another means, after the user has
   submitted his/her choice. For instance I might have a text file
   like:

         banana,yellow
         apple,red
         orange,orange

    So in the template for the mail sent to the user, something like 
   this should appear:

            Favourite fruit: ###fruit###
            Color of the fruit: ###fruit_color###

    Is there any way to get this? I tried by using a post-processing
    function as suggested on http://typo3.org/documentation/document-
library/extension-manuals/th_mailformplus/4.0.5/view/1/5/#id3823153
    but it does not work: it looks like I cannot actually add
    new fields or modify the ones supplied by the user. At the least
    not with such a syntax:

<?php
class myform_postproc {
function doit(&$params, &$ref){
  (...)
  $params["data"]["fruit_color"]="(got it somewhere)"; 
}
}
?>

    BTW, I thought the right syntax to reach the fields supplied by the
    user was $params[fieldname], but after some tests I saw that I can
    see their values only through $params["data"][fieldname].

2. Is there any way to send out the output of the form to the final
   target, both in text and HTML format (provided both have been 
   configured in the template), as a multipart/mixed instead of
   multipart/alternative document? I need to make both formats
   available to the user at the same time, not just one as an
   alternative to the other.

Thanks in advance

Claudio