Email script error message RCPT

Code:
-- send an e-mail

function mail(to, subject, message)

  -- make sure these settings are correct

  local settings = {

    -- "from" field, only e-mail must be specified here

    from = 'xxxxx',

    -- smtp username

    user = 'xxxxx',

    -- smtp password

    password = 'xxxxx',

    -- smtp server

    server = 'smtp01.binero.se',

    -- smtp server port

    port = 465,

    -- enable tls, required for gmail smtp

    secure = 'sslv23',

  }



  local smtp = require('socket.smtp')



  if type(to) ~= 'table' then

    to = { to }

  end



  for index, email in ipairs(to) do

    to[ index ] = '<' .. tostring(email) .. '>'

  end



  -- fixup from field

  local from = '<' .. tostring(settings.from) .. '>'



  -- message headers and body

  settings.source = smtp.message({

    headers = {

      to = table.concat(to, ', '),

      subject = subject,

      ['From'] = from,

      ['Content-type'] = 'text/html; charset=utf-8',

    },

    body = message

  })



  settings.from = from

  settings.rcpt = to



  return smtp.send(settings)

end