title: How to check programmatically if an email is existing or not
body: <p>How to write a code to check an email is existing or not? For example donkey_sdh123@gmail.com, donkey_sdh123@yahoo.com, or donkey_sdh123@lycos.com all these emails do not exist in gmail, yahoo and lycos database. <br>
  <img src="https://i.stack.imgur.com/fOOqj.png" alt="enter image description here"></p>
  
  <p><br></p>
  
  <p>See the screenshot. donkey_sdh123@gmail.com is bad. That means it does not exist. how can i implement the same thing in my project?</p>
  
  <p>javascript, jquery shell script, c or c++ are welcome. Without .net.</p>