title: Telethon write a message/start a chat after button - bot send message before /start
body: <p>I'm trying to write an access bot with telethon for telegram.</p>
  <ol>
  <li>User added to the group or join with an invite link.</li>
  <li>Get restricted and have to push a button.</li>
  <li>The bot write a simple captcha message like &quot;1+2=?&quot;</li>
  <li>And if it's right, the person gets unrestricted and if wrong, gets kicked out...</li>
  </ol>
  <p>Everything works pretty fine but:<br />
  If the new joined and user don't write first &quot;/start&quot;, the user doesn't get a message from the bot.</p>
  <p>Is there any possibility that the person receives the message anyway?</p>
  <p>I've read it is not possible to do that somewhere, but there are bots outside how do that?</p>