Views Bulk Operations (VBO) has a send email action that sends you to an email form. How can I add a views field to a list of users that creates a link to the same action form that VBO uses to send email, but for just that user row and then pre-populate the recipient field? I believe VBO uses the system_send_email_action_form.
In order to do this with VBO you'll need modify the
system_send_email_action_form form (to default its recipient) and add some custom JS (to create click events that automatically submit the VBO form).
An easier alternative here is to use the Views Send module which does nearly the same thing with a slight UI difference; there's a Send Email button at the bottom of the view as opposed to a send email link for each row.