function isMail(leChamp)
    {
    if (leChamp=="") return false;
    else
            {
            if (leChamp.indexOf("@")==-1) return false;
            else
            {
                    longueur = leChamp.length;
                    position = leChamp.indexOf("@");
                    left_str = leChamp.substring(0,position);
                    right_str = leChamp.substring(position+1,longueur);
                    left_len = left_str.length;
                    right_len = right_str.length;
                    if ((left_len==0) || (right_len==0)) return false;
                    else
                    {
                            if (right_str.indexOf(".")==-1) return false;
                            else
                            {
                                    right_longueur = right_str.length;
                                    right_position = right_str.lastIndexOf(".");
                                    l_right_str = right_str.substring(0,right_position);
                                    r_right_str = right_str.substring(right_position+1,right_longueur);
                                    l_right_len = l_right_str.length;
                                    r_right_len = r_right_str.length;
                                    if ((r_right_len < 2)||(r_right_len > 4)) return false;
                                    else if (l_right_len==0) return false;
                            }
                    }
            }
    }
    return true;
    }

function test(leform)
	{
		if (leform.txt_email.value == '' || isMail(leform.txt_email.value) != true)
			{
				alert('Vous devez saisir un email valide.');
				leform.txt_email.focus();
				return false;
			}
		return true;
	}