Send an email from unity to email adress?

You will need to use a server-side script (PHP,ASP.NET) to serves as a relay on some webhost. This isn't really related to Unity, but here's the shortest possible example: Note this is more informative than actual implementation.

PHP:

 <?php
         $address = $_GET["address"];
         $subject= $_GET["subject"];
         $object= $_GET["object"];
        
         mail($address,$subject,$object);
 ?>

Unity C#:

 string baseURL = "http://www.mywebhost.com/myscript.php?address=%address%&subject=%subject%&object=%object%";
 IEnumerator Email(string address, string subject, string object)
 {
         string url = baseURL;
         url = url.Replace("%address%,address);
         url = url.Replace("%subject%,subject);
         url = url.Replace("%object%,object);
  
         WWW www = new WWW(url);
         yield return www;
 }