Prefilled send form

Issue Summary

Hi,
I have a little problem with the module send. I want to alter the send form so I get the senders fields prefilled with logged user's information. The problem is that when I dumped the $form in my hook_form_alter, i do not see the fields of mail, last name and first name. My question is: can I prefill the send form fields with user's informations???

Thank you in advance.