title: Telegram API: doesn't send message to user until receive first message from that user
body: <p>I use Telegram API to send a message to a user with my bot.
  When the user sends me a message, that operation works but when I want to send a message to an user that haven't sent me any message to me before, then an error occurs (I have his user id):</p>
  
  <pre><code>{"ok":false,"error_code":400,"description":"Error: Bad Request: user not found"}
  </code></pre>
  
  <p>Is there a solution to solve this?</p>