recommending friends, using RoR's Mailer

Hi there, I wan tto be able to allow users to invite friends...

The action below is exactly the same as the code used to send a user
their username. Only difference is, I need to change the ''user =
User.find_by_email(email)'' part as obviously, I dont want to only
email people who are already on the site.

  def invite
        @title = "Invitation"

        if param_posted?(:user)
          email = params[:user][:email]
          user = User.find_by_email(email)
          if user
          UserMailer.deliver_invite(@user)
          flash[:notice] = "Invite sent."
          redirect_to :action => "index", :controller => "site"
          else
          flash[:notice] = "There is no user with that email
address."
        end
      end
    end

The UserMailer code is below:
  def invite(user)
      @subject = 'Invitation'
      @body = {}
    # Give body access to the user information.
      @body["user"] = user
      @recipients = user.email
      @from = '<do-not-reply@domainname.com>'

  end

The last part is the call to the UserMailer that picks the template to
send the relevant email..

UserMailer.deliver_invite(@user)

the _invite is the template in which is ultimately displayed to the
chosen invitee.

ANy ideas how this can be altered to allow for the mail to be sent to
anyone added to the input field?

Many Thanks