<form method="post" action="formmail.php">
  <fieldset>
    <legend>Contact</legend>
        <br /><br />
        <label for="mail">Chemins de Relais</label>
        <INPUT type="radio" name="mail" value="cdr">
        <label for="adresse">Relais</label>
        <INPUT type="radio" name="mail" value="r">
        <label for="adresse">Association Relais</label>
        <INPUT type="radio" name="mail" value="ar">
        <br /><br />
    <label>Nom :</label>
    <input type="text" name="nom">
    <br /><br />
    <label>Mail :</label>
    <input type="text" name="adresse">
        <br /><br />
        <label>Message :</label><br />
        <textarea name="message" rows="10" cols="25"></textarea>
        <br /><br />
        <input type="submit" value="Envoyer">
        <br /><br />
  </fieldset>
</form>

<?php

/*...............................................................................Valeurs des champs input..............................................................*/

$nom=$_post['nom'];
$adresse=$_post['adresse'];
$message=$_post['message'];
$mailselected=$_post['mail'];



$contenu=$nom;
$contenu .=$mail;
$contenu .=$message;
/*................................................................................Variables des trois adresses mails des associations RELAIS...*/

$cheminsderelais= "phyloceur@gmail.com";
$relais= "reseau.relais@wanadoo.fr";
$siegesocial= "relais.asso@wanadoo.fr";

/*................................................................................Conditions pour l'envoie des mails..............................................*/

if ( $mailselected=='cdr' AND isset($_post['nom']) AND isset($_post['adresse']) AND isset($_post['message'])   )
{
mail($cheminsderelais, $contenu);
echo "ça marche";
}
elseif ( $mailselected=='r' AND isset($_post['nom']) AND isset($_post['adresse']) AND isset($_post['message'])   )
{
mail($relais, $contenu);
echo "ça marche";
}
elseif ( $mailselected=='ar' AND isset($_post['nom']) AND isset($_post['adresse']) AND isset($_post['message'])   )
{
mail($siegesocial, $contenu);
echo "ça marche";
}
else {
echo "Ca ne marche pas!";
}
?>