diff --git a/src/pretix/base/migrations/0198_invoice_sent_to_customer.py b/src/pretix/base/migrations/0198_invoice_sent_to_customer.py
new file mode 100644
index 0000000000..a82a362f59
--- /dev/null
+++ b/src/pretix/base/migrations/0198_invoice_sent_to_customer.py
@@ -0,0 +1,21 @@
+# Generated by Django 3.2.4 on 2021-09-30 10:25
+from datetime import datetime
+
+from django.db import migrations, models
+from pytz import UTC
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0197_auto_20210914_0814'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='invoice',
+            name='sent_to_customer',
+            field=models.DateTimeField(blank=True, null=True, default=UTC.localize(datetime(1970, 1, 1, 0, 0, 0, 0))),
+            preserve_default=False,
+        ),
+    ]
diff --git a/src/pretix/base/models/invoices.py b/src/pretix/base/models/invoices.py
index a4344cea11..54cf70fd7f 100644
--- a/src/pretix/base/models/invoices.py
+++ b/src/pretix/base/models/invoices.py
@@ -159,6 +159,8 @@ class Invoice(models.Model):
     # False: The invoice wasn't sent and never will, because sending was not configured at the time of the check.
     sent_to_organizer = models.BooleanField(null=True, blank=True)
 
+    sent_to_customer = models.DateTimeField(null=True, blank=True)
+
     file = models.FileField(null=True, blank=True, upload_to=invoice_filename, max_length=255)
 
     objects = ScopedManager(organizer='event__organizer')
diff --git a/src/pretix/base/services/invoices.py b/src/pretix/base/services/invoices.py
index c0c49c8357..7de971b41e 100644
--- a/src/pretix/base/services/invoices.py
+++ b/src/pretix/base/services/invoices.py
@@ -291,6 +291,7 @@ def generate_cancellation(invoice: Invoice, trigger_pdf=True):
     cancellation.payment_provider_text = ''
     cancellation.file = None
     cancellation.sent_to_organizer = None
+    cancellation.sent_to_customer = None
     with language(invoice.locale, invoice.event.settings.region):
         cancellation.invoice_from = invoice.event.settings.get('invoice_address_from')
         cancellation.invoice_from_name = invoice.event.settings.get('invoice_address_from_name')
@@ -346,8 +347,8 @@ def invoice_pdf_task(invoice: int):
             i.file.delete()
         with language(i.locale, i.event.settings.region):
             fname, ftype, fcontent = i.event.invoice_renderer.generate(i)
-            i.file.save(fname, ContentFile(fcontent))
-            i.save()
+            i.file.save(fname, ContentFile(fcontent), save=False)
+            i.save(update_fields=['file'])
             return i.file.name
 
 
diff --git a/src/pretix/base/services/mail.py b/src/pretix/base/services/mail.py
index 82360f45b0..02d2be1ac9 100644
--- a/src/pretix/base/services/mail.py
+++ b/src/pretix/base/services/mail.py
@@ -57,7 +57,7 @@ from django.core.mail import (
 from django.core.mail.message import SafeMIMEText
 from django.db import transaction
 from django.template.loader import get_template
-from django.utils.timezone import override
+from django.utils.timezone import now, override
 from django.utils.translation import gettext as _, pgettext
 from django_scopes import scope, scopes_disabled
 from i18nfield.strings import LazyI18nString
@@ -438,6 +438,7 @@ def mail_send_task(self, *args, to: List[str], subject: str, body: str, html: st
 
             email = email_filter.send_chained(event, 'message', message=email, order=order, user=user)
 
+        invoices_sent = []
         if invoices:
             invoices = Invoice.objects.filter(pk__in=invoices)
             for inv in invoices:
@@ -449,6 +450,7 @@ def mail_send_task(self, *args, to: List[str], subject: str, body: str, html: st
                                 inv.file.file.read(),
                                 'application/pdf'
                             )
+                        invoices_sent.append(inv)
                     except:
                         logger.exception('Could not attach invoice to email')
                         pass
@@ -558,6 +560,10 @@ def mail_send_task(self, *args, to: List[str], subject: str, body: str, html: st
                 )
             logger.exception('Error sending email')
             raise SendMailException('Failed to send an email to {}.'.format(to))
+        else:
+            for i in invoices_sent:
+                i.sent_to_customer = now()
+                i.save(update_fields=['sent_to_customer'])
 
 
 def mail_send(*args, **kwargs):
diff --git a/src/pretix/control/templates/pretixcontrol/order/index.html b/src/pretix/control/templates/pretixcontrol/order/index.html
index 9739df9578..2dece2d272 100644
--- a/src/pretix/control/templates/pretixcontrol/order/index.html
+++ b/src/pretix/control/templates/pretixcontrol/order/index.html
@@ -234,7 +234,23 @@
                                 {% for i in invoices %}
                                     <a href="{% url "control:event.invoice.download" invoice=i.pk event=request.event.slug organizer=request.event.organizer.slug %}">
                                         {% if i.is_cancellation %}{% trans "Cancellation" context "invoice" %}{% else %}{% trans "Invoice" %}{% endif %}
-                                        {{ i.number }}</a> ({{ i.date|date:"SHORT_DATE_FORMAT" }})
+                                        {{ i.number }}</a>
+                                    ({{ i.date|date:"SHORT_DATE_FORMAT" }})
+                                    {% if i.sent_to_customer.year == 1970 %}
+                                        <span class="fa-stack fa-stack-small" data-toggle="tooltip" title="{% trans "We don't know if this invoice was emailed to the customer since it was created before our system tracked this information" %}">
+                                            <span class="fa fa-background fa-envelope text-muted fa-stack-1x"></span>
+                                            <span class="fa fa-question fa-stack-1x fa-stack-shifted"></span>
+                                        </span>
+                                    {% elif i.sent_to_customer %}
+                                        <span class="fa-stack fa-stack-small" data-toggle="tooltip" title="{% trans "Invoice was emailed to customer" %}">
+                                            <span class="fa fa-background fa-envelope text-muted fa-stack-1x"></span>
+                                            <span class="fa fa-check text-success fa-stack-1x fa-stack-shifted"></span>
+                                        </span>
+                                    {% else %}
+                                        <span class="fa-stack fa-stack-small" data-toggle="tooltip" title="{% trans "Invoice was not yet emailed to customer" %}">
+                                            <span class="fa fa-background fa-envelope text-muted fa-stack-1x"></span>
+                                        </span>
+                                    {% endif %}
                                     {% if not i.canceled %}
                                         {% if request.event.settings.invoice_regenerate_allowed %}
                                             <form class="form-inline helper-display-inline" method="post"
@@ -268,6 +284,12 @@
                                         <br/>
                                     {% endif %}
                                 {% endfor %}
+                                {% if invoices_send_link %}
+                                    <br/>
+                                    <a class="btn btn-default btn-xs" href="{{ invoices_send_link }}">
+                                        {% trans "Email invoices" %}
+                                    </a>
+                                {% endif %}
                                 {% if can_generate_invoice %}
                                     <br/>
                                     <form class="form-inline helper-display-inline" method="post"
diff --git a/src/pretix/control/views/orders.py b/src/pretix/control/views/orders.py
index eff84da2ec..031474875a 100644
--- a/src/pretix/control/views/orders.py
+++ b/src/pretix/control/views/orders.py
@@ -65,7 +65,7 @@ from django.utils.formats import date_format, get_format
 from django.utils.functional import cached_property
 from django.utils.http import is_safe_url
 from django.utils.timezone import make_aware, now
-from django.utils.translation import gettext, gettext_lazy as _
+from django.utils.translation import gettext, gettext_lazy as _, ngettext
 from django.views.generic import (
     DetailView, FormView, ListView, TemplateView, View,
 )
@@ -313,6 +313,27 @@ class OrderDetail(OrderView):
         ctx['download_buttons'] = self.download_buttons
         ctx['payment_refund_sum'] = self.order.payment_refund_sum
         ctx['pending_sum'] = self.order.pending_sum
+
+        unsent_invoices = [ii.pk for ii in ctx['invoices'] if not ii.sent_to_customer]
+        if unsent_invoices:
+            ctx['invoices_send_link'] = reverse('control:event.order.sendmail', kwargs={
+                'event': self.request.event.slug,
+                'organizer': self.request.event.organizer.slug,
+                'code': self.order.code
+            }) + '?' + urlencode({
+                'subject': ngettext('Your invoice', 'Your invoices', len(unsent_invoices)),
+                'message': ngettext(
+                    'Hello,\n\nplease find your invoice attached to this email.\n\n'
+                    'Your {event} team',
+                    'Hello,\n\nplease find your invoices attached to this email.\n\n'
+                    'Your {event} team',
+                    len(unsent_invoices)
+                ).format(
+                    event="{event}",
+                ),
+                'attach_invoices': unsent_invoices
+            }, doseq=True)
+
         return ctx
 
     @cached_property
@@ -1954,6 +1975,8 @@ class OrderSendMail(EventPermissionRequiredMixin, OrderViewMixin, FormView):
             kwargs['initial']['subject'] = self.request.GET.get('subject')
         if self.request.GET.get('message'):
             kwargs['initial']['message'] = self.request.GET.get('message')
+        if self.request.GET.getlist('attach_invoices'):
+            kwargs['initial']['attach_invoices'] = self.order.invoices.filter(pk__in=self.request.GET.getlist('attach_invoices'))
         return kwargs
 
     def form_invalid(self, form):
diff --git a/src/pretix/static/pretixbase/scss/_theme.scss b/src/pretix/static/pretixbase/scss/_theme.scss
index 1bea412b72..d3126e6e41 100644
--- a/src/pretix/static/pretixbase/scss/_theme.scss
+++ b/src/pretix/static/pretixbase/scss/_theme.scss
@@ -203,6 +203,19 @@ svg.svg-icon {
   opacity: 0.7;
 }
 
+.fa-background {
+  opacity: 0.3;
+}
+
+.fa-stack-small {
+  width: 1.6em;
+  height: 1em;
+  line-height: 1em;
+}
+.fa-stack-shifted {
+  left: 0.5em;
+}
+
 @include table-row-variant('success', lighten($brand-success, 40%));
 @include table-row-variant('info', lighten($brand-info, 30%));
 @include table-row-variant('warning', lighten($brand-warning, 40%));