def deliver!(mail)
      envelope = Mail::SmtpEnvelope.new(mail)
      response = smtp.sendmail(dot_stuff(envelope.message), envelope.from, envelope.to)
      settings[:return_response] ? response : self
    end
def deliver!(mail)
      envelope = Mail::SmtpEnvelope.new(mail)
      response = smtp.sendmail(dot_stuff(envelope.message), envelope.from, envelope.to)
      settings[:return_response] ? response : self
    end
Send the message via SMTP.
 The from and to attributes are optional. If not set, they are retrieve from the Message.