Populate send message to field with variable

Hi,
Your plugin is good. Thanks for the work.
I will buy the paid version if this functionality is possible.
I need to be able to send a message from a page to a third person that is neither the user nor the page author, but who is a registered user.
After clicking on a choice in a foreach loop, the current user chooses a project that was created by another user (user B). I want to send a message to user B.
Once that user B is chosen I have his email/nicename within a variable on the page, so can I implement that variable as a prepoulated to: field?
Thanks for your help.
Rich Roberts