php mailler yardım

merhaba arkadaşlar
aşagıdakı kod çalışıyor fakat checkbox seçim yapılmasa dahı hepsi seçili olarak gıdıyor maıle. sadece secılı olanlar maıl adresıne nasıl gonderılır ?

<script>
function _(id){ return document.getElementById(id); }
function submitForm(){
    _("mybtn2").disabled = true;
    _("status").innerHTML = 'Lütfen bekleyin ...';
    var formdata = new FormData();
    formdata.append( "mmm1", _("mmm1").value );
    formdata.append( "mmm2", _("mmm2").value );
    formdata.append( "mmm3", _("mmm3").value );
    formdata.append( "mmm4", _("mmm4").value );
    formdata.append( "mmm5", _("mmm5").value );
    formdata.append( "mmm6", _("mmm6").value );
    formdata.append( "mmm7", _("mmm7").value );
    formdata.append( "mmm8", _("mmm8").value );

    var ajax = new XMLHttpRequest();
    ajax.open( "POST", "formmail2/mail.php" );
    ajax.onreadystatechange = function() {
        if(ajax.readyState == 4 && ajax.status == 200) {
            if(ajax.responseText == "Gönderme başarılı"){
                _("my_form2").innerHTML = '<h2>Teşekkürler, mesajınız İletilmiştir.</h2>';
            } else {
                _("status").innerHTML = ajax.responseText;
                _("mybtn2").disabled = false;
            }
        }
    }
    ajax.send( formdata );
}
</script>

                            <!-- quote form start here -->
                            <section class="quote-form">
                                <form id="my_form2" onsubmit="submitForm(); return false;">
                                    <fieldset>
                                        <div class="form-group">
                                            <input type="text" name="mmm1" id="mmm1" placeholder="Ad Soyad" class="form-control" required data-error="NEW ERROR MESSAGE">
                                        </div>
                                        <div class="form-group">
                                            <input type="email" name="mmm2" id="mmm2" placeholder="Mail" class="form-control" required data-error="NEW ERROR MESSAGE">
                                        </div>
                                        <div class="form-group">
                                            <input type="tel" name="mmm3" id="mmm3" placeholder="Telefon" class="form-control" required data-error="NEW ERROR MESSAGE">
                                        </div>
                                        <div class="form-group">
                                            <input type="text" name="mmm4" id="mmm4" placeholder="Firma Adı" class="form-control" required data-error="NEW ERROR MESSAGE">
                                        </div>
                                        
                                        <div class="col-xs-12 col-sm-6 col-md-6">
                                        <div class="form-group" style="margin: 0 0 0px;">
                                        <ul>
                                        <li><input type="checkbox" id="mmm5" name="mmm5" value="Seçim 1"><label> Seçim 1</label></li>
                                        <li><input type="checkbox" id="mmm6" name="mmm6" value="Seçim 2"><label> Seçim 2</label></li>
                                        <li><input type="checkbox" id="mmm7" name="mmm7" value="Seçim 3"><label> Seçim 3</label></li>
                                        <li><input type="checkbox" id="mmm8" name="mmm8" value="Seçim 4"><label> Seçim 4</label></li>
                                        </ul>
                                        </div>
                                        </div>

                                        
                                        <span id="status"></span>

                                        <button class="btn btn-default main-bg-color" type="submit" id="mybtn2">Teklif Al</button>
                                    </fieldset>
                                </form>
                            </section>
                            <!-- quote form end here -->

<section class="quote-form">
    <form id="my_form2">
        <fieldset>
            <div class="form-group">
                <input type="text" name="mmm1" id="mmm1" placeholder="Ad Soyad" class="form-control" required data-error="NEW ERROR MESSAGE">
            </div>
            <div class="form-group">
                <input type="email" name="mmm2" id="mmm2" placeholder="Mail" class="form-control" required data-error="NEW ERROR MESSAGE">
            </div>
            <div class="form-group">
                <input type="tel" name="mmm3" id="mmm3" placeholder="Telefon" class="form-control" required data-error="NEW ERROR MESSAGE">
            </div>
            <div class="form-group">
                <input type="text" name="mmm4" id="mmm4" placeholder="Firma Adı" class="form-control" required data-error="NEW ERROR MESSAGE">
            </div>

            <div class="col-xs-12 col-sm-6 col-md-6">
                <div class="form-group" style="margin: 0 0 0px;">
                    <ul>
                        <li><input type="checkbox" id="mmm5" name="mmm5" value="Seçim 1"><label> Seçim 1</label></li>
                        <li><input type="checkbox" id="mmm6" name="mmm6" value="Seçim 2"><label> Seçim 2</label></li>
                        <li><input type="checkbox" id="mmm7" name="mmm7" value="Seçim 3"><label> Seçim 3</label></li>
                        <li><input type="checkbox" id="mmm8" name="mmm8" value="Seçim 4"><label> Seçim 4</label></li>
                    </ul>
                </div>
            </div>


            <span id="status"></span>

            <button class="btn btn-success main-bg-color" type="submit" id="mybtn2">Teklif Al</button>
        </fieldset>
    </form>
</section>

    function _(id){ return document.getElementById(id); }

    _("my_form2").addEventListener("submit", e => {
        e.preventDefault()
        _("mybtn2").disabled = true;
        _("status").innerHTML = 'Lütfen bekleyin ...';
        let fd = new FormData();
        [...document.querySelectorAll("#my_form2 input:not(input[type='checkbox'])")].forEach(value => {
            fd.append(value.getAttribute("name"), value.value)
        });
        [...document.querySelectorAll("#my_form2 input[type='checkbox']")].forEach(value => {
           if (value.checked)
               fd.append(value.getAttribute("name"), value.value)
        });
        let ajax = new XMLHttpRequest();
        ajax.open( "POST", "ajax.php" );
        ajax.onreadystatechange = function() {
            if(ajax.readyState === 4 && ajax.status === 200) {
                if(ajax.responseText === "Gönderme başarılı"){
                    _("my_form2").innerHTML = '<h2>Teşekkürler, mesajınız İletilmiştir.</h2>';
                } else {
                    _("status").innerHTML = ajax.responseText;
                    _("mybtn2").disabled = false;
                }
            }
        }
        ajax.send(fd);
    })

@Abdullahx; çok teşekkür ederim