PHP form email validation -

my mail form still sending emails if email address not valid. example, if fill in email "bob", , hit submit, javascript validator gives warning message, email still goes through. ends in spam box bob@mydomain.com

how can validate email address, , prevent submit if not validate?

i new php.

html:

 <div id="emailform">                 <h2>confirm purchase information</h2>                 <hr>                 <form method="post" name="contactform" action="mail_form.php" id="submit">                 <p>                 <label for='name'>your name:</label> <br>                 <input type="text" name="name">                 </p>                 <p>                 <label for='email'>email address:</label> <br>                 <input type="text" name="email">                 </p>                 <p>                 <label for='purchasecode'>purchase code:</label> <br>                 <input type="text" name="purchasecode">                 </p>                 <p>                 <label for='vendor'>vendor name:</label> <br>                 <select name="vendor">                   <option value="" selected="selected"></option>                   <option value="amazon" >amazon</option>                   <option value="barnes&noble" >barnes &amp; noble</option>                   <option value="family christian" >family christian</option>                   <option value="christianbook" >christianbook.com</option>                   <option value="lifeway" >lifeway</option>                   <option value="bam" >books-a-million</option>                   <option value="mardel" >mardel</option>                 </select>                 </p>                 <button type="submit" id="submitbutton" name="submit" value="submit" class="mainbutton">submit</button><br>                 </form>  <!--            code validating form                 visit http://www.javascript-coder.com/html-form/javascript-form-validation.phtml                 details -->                 <script type="text/javascript">                 var frmvalidator  = new validator("contactform");                 frmvalidator.addvalidation("name","req","please provide name");                 frmvalidator.addvalidation("email","email","please enter valid email address");                 frmvalidator.addvalidation("vendor","dontselect=000");                 frmvalidator.addvalidation("purchasecode","maxlen=50");                 </script>             </div> 

php:

<?php ini_set('display_errors',1);  error_reporting(e_all);  if(!isset($_post['submit'])) {   //this page should not accessed directly. need submit form.   echo "error; need submit form!"; } $name = $_post['name']; $email = $_post['email']; $purchasecode = $_post['purchasecode']; $vendor = $_post['vendor'];   //validate first if(empty($_post['name'])  ||    empty($_post['email']) ||    empty($_post['purchasecode']) ||    empty($_post['vendor'])) {     echo "all fields required."; exit; }  if(isinjected($email)) {     echo "bad email value!";     exit; }  $email_from = $email; $email_subject = "gdfy purchase confirmation"; $email_body = "new purchase confirmation $name.\n".     "here details:\n\n name: $name \n\n email: $email \n\n purchase code: $purchasecode \n\n vendor: $vendor";  $to = "idc615@gmail.com";//<== update email address  $headers = "from: $email_from \r\n"; $headers .= "reply-to: $email_from \r\n"; //send email! mail($to,$email_subject,$email_body,$headers); //done. redirect thank-you page. header('location: index.html');  // echo "success";   // function validate against email injection attempts function isinjected($str) {   $injections = array('(\n+)',               '(\r+)',               '(\t+)',               '(%0a+)',               '(%0d+)',               '(%08+)',               '(%09+)'               );   $inject = join('|', $injections);   $inject = "/$inject/i";   if(preg_match($inject,$str))     {     return true;   }   else     {     return false;   } }  ?> 

javascript:

  $('#submit').submit(function() { // catch form's submit event       $.ajax({ // create ajax call...           data: $(this).serialize(), // form data           type: $(this).attr('method'), // or post           url: $(this).attr('action'), // file call           success: function(response) { // on success..               $('#emailform').html("<h2 style='text-align:center;'>thank you!</h2><hr><p style='text-align:center;'>thank submitting purchase information.<br>we send free gifts soon!</p>"); // update div           }       });       return false; // cancel original event prevent form submitting   }); 

you can use filter_var :

if( filter_var('bob@example.com', filter_validate_email) ) {     do_stuff(); }