php: get post results from multiple forms through one submit - php

Question

I have a table with a list of clients, then a "modify" button then a "delete" button, and then a "add to mailing list" checkbox, each of these elements is its own form. There is also a selector at the end to chose which mailing list to add the address to.
My problem is with these checkboxes.
I have one submit button at the end of the table to add all of the checked emails to a file, but it only works on the last email address.
Here is the code for the checkboxes:
echo "<td>";
echo "<form action=\"\" method=\"post\">";
if($email!="" && $email!=null){
echo "<label class=\"checkbox-inline\">
<input type=\"checkbox\" name=\"mailing[]\" value=\"".$email[0][0]."\" title=\"".$email[0][0]."\"><span><i class=\"glyphicon glyphicon-envelope\"></i></span></label>";
}else{
echo "<label class=\"checkbox-inline\">
<input type=\"checkbox\" disabled><span><i class=\"glyphicon glyphicon-envelope\"></i></span></label>";
}
echo "</form>";
echo "</td>";
//... more code
//selector + submit
<form action="" method="post">
<div class="col-sm-6 pull-right">
<label class="control-label">Ajouter ces adresses à la liste:</label>
<select class="form-control" name="liste">
<option value=""></option>
<?php
$linkpdo = openConnection();
$req = $linkpdo->prepare('SELECT * FROM AERA.mailing');
$req->execute();
$lists = $req->fetchAll();
if(count($lists)<>0){
for ($i = 0; $i < count($lists) ; $i++){
echo "<option value=\"".$lists[$i][0]."\">";
echo $lists[$i][1];
echo "</option>";
}
}
?>
</select>
</br>
<button type="submit" class="btn btn-info" id="clickAll">Ajouter</button>
How can I get all of the checkbox values? Or is there another way to go about it? Thanks
UPDATE
Here is how I am currently handling the results:
if(!empty($_POST['mailing'])) {
foreach ($_POST['mailing'] as $key => $value){
$mailing=$_POST['mailing'][$key];
if(stripos(file_get_contents($filename), $mailing)!== false){
echo '<div class="container">
<div class="col-sm-6 col-sm-offset-3 alert alert-info">
<p class="text-center">Vous avez essayé d\'insérer des doublons.</br>Ces valeurs n\'ont pas été prises en compte</p>
</div>
</div>';
}else{
$stringIn.=$mailing.", ";
}
}
}

Answer 1

Why don't you make a html form and than a php script?
you can see an example here: Getting checkbox values on submit