On click of checkbox send email to selected recipients using module &lt;script type="text/javascript"&gt;
 function send_email(){
 var persons_names;
 persons_names = $('#send_mail_persons input:checked');
 var persons_names_Str='',coma='';
 if(persons_names.length != 0){
 persons_names.each(function(){
     persons_names_Str += coma+$(this).val();
     coma = ',';
 })
 }
 alert(persons_names_Str);
 //    console.log(" persons_names_Str: "+persons_names_Str);
 ajax_call_to_send_values_to(persons_names_Str);
 }


 function ajax_call_to_send_values_to(persons_names_Str){
 $.ajax({
              url: 'http://&lt;?php echo $_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'];?  &gt;',
            type: 'POST',
              data: { persons_names_Str: persons_names_Str            
                       },  
              success: function(data, textStatus, xhr) {

              },
            //called when successful

              error: function(xhr, textStatus, errorThrown) {
            //called when there is an error
                  }
    });
 }
 &lt;/script&gt;

 &lt;?php
 if( isset($_POST['persons_names_Str']) &amp;&amp; !empty($_POST['persons_names_Str']) )
  {
 $list = $_POST['persons_names_Str'];
 //print_r($list);
 //$to_arr = explode(",", $list);
 //$to = array_filter($to_arr);
 //echo $to;
 //print_r($to);
 $to = $list;
 $subject = "Test Subject";
 $body = "This is temporary email from Lawandmoney. ";
 $headers = "From: no-reply@lawandmoney.com\r\n" .
 "X-Mailer: php";

 $to =  "no-reply@lawandmoney.com";
 $headerFields = array('BCC: '.$list.', "From: no-reply@lawandmoney.com" ."X-Mailer:    php"');
 if (mail($to, $subject, $body, implode("\r\n", $headerFields))) {
 //if (mail($to, $subject, $body, $headers)) {
  echo("&lt;p&gt;Message sent successfully! our lawyer will contact you as soon as   possible&lt;/p&gt;");
  } else {
  echo("&lt;p&gt;Message delivery failed...&lt;/p&gt;");
  }
  exit();
  }  

  ?&gt;

  &lt;div id="send_mail_persons"&gt;
  &lt;?php
   $sql = "SELECT * FROM lawyer_details WHERE city LIKE :city AND speciality LIKE   :speciality";
   $result = db_query($sql,array(':city' =&gt; '%'.  db_like($_SESSION['selected_county']).'%' , ':speciality' =&gt;  '%'.db_like($_SESSION['lawarea']).'%'));

 $rows_count=$result-&gt;rowCount();

 if($result &amp;&amp; $rows_count&gt;0) 
 { 
 while($row = $result-&gt;fetchAssoc()) 
 {
  ?&gt;
  &lt;div class="result"&gt;
   &lt;div class="resultPadder"&gt;
       &lt;div class="resultLeft"&gt;
          &lt;div id="fav"&gt;
         &lt;div&gt;&lt;input type="checkbox" name="checkbox[]" id="email1" value=&lt;?php echo  $row['email_id'];?&gt; /&gt;&lt;a class="b ui-link" href="" onclick=""&gt;&lt;?php echo  $row['first_name'].' '.$row['middle_name'].' '.$row['last_name'];?&gt;&lt;/a&gt;  
          &lt;/div&gt;
       &lt;div class="p-t-2"&gt;&lt;?php echo $row['street_address'];?&gt;&lt;/div&gt;
       &lt;/div&gt;
       &lt;/div&gt;
  &lt;div class="resultRight"&gt;


 &lt;/div&gt;&lt;/div&gt;&lt;div class="clear"&gt;&lt;/div&gt;


 &lt;?php 

  }
  }
 else
  {
 echo "No Result Found";
 }
 ?&gt;
 &lt;a href="javascript:void(0);"  onClick="javascript:send_email();"&gt;&lt;span&gt;Send  Email&lt;/span&gt;&lt;/a&gt;

 &lt;/div&gt;
 &lt;/div&gt;
 &lt;div&gt;


only just add jquery file in head section.
"to" parameter in drupal_mail is a string. You can have as many receipent as you like in the the emails "to" string, provided they are separated by commas (",").
You can do like this

$to  = 'one@email.com, two@email.com, three@email.com';
drupal_mail('$module_name', $key, $to, language_default(), $params = array('username' =&gt; 'test'), $from = NULL, $send = TRUE);


You may check the documentation of drupal_mail.