It is unfortunately not possible to insert a form, Javascript or Flash, into a newsletter. Not many e-mail clients supports these formats, and they have an adverse effect towards spamfilters.
This means that, for example, that Facebook's Like-code cannot be used in newsletters as it is build upon Javascript and iframe-code. As an alternative you can use the 'sharing function'.
If you wish to "insert" a form, you can instead link to a website, where the form is located, and that way let your recipients fill it out. For Javascript and Flash there is no good alternative.
