diff --git a/src/pretix/base/services/orders.py b/src/pretix/base/services/orders.py
index 63b0d7a2f9..3a38339973 100644
--- a/src/pretix/base/services/orders.py
+++ b/src/pretix/base/services/orders.py
@@ -64,9 +64,9 @@ from pretix.base.i18n import (
     LazyLocaleException, get_language_without_region, language,
 )
 from pretix.base.models import (
-    CartPosition, Device, Event, GiftCard, Item, ItemVariation, Membership,
-    Order, OrderPayment, OrderPosition, Quota, Seat, SeatCategoryMapping, User,
-    Voucher,
+    CartPosition, Customer, Device, Event, GiftCard, Item, ItemVariation,
+    Membership, Order, OrderPayment, OrderPosition, Quota, Seat,
+    SeatCategoryMapping, User, Voucher,
 )
 from pretix.base.models.event import SubEvent
 from pretix.base.models.orders import (
@@ -849,7 +849,7 @@ def _get_fees(positions: List[CartPosition], payment_requests: List[dict], addre
 def _create_order(event: Event, email: str, positions: List[CartPosition], now_dt: datetime,
                   payment_requests: List[dict], locale: str=None, address: InvoiceAddress=None,
                   meta_info: dict=None, sales_channel: str='web', shown_total=None,
-                  customer=None):
+                  customer=None, customer_attached=False):
     payments = []
     sales_channel = get_all_sales_channels()[sales_channel]
 
@@ -931,6 +931,8 @@ def _create_order(event: Event, email: str, positions: List[CartPosition], now_d
         if meta_info:
             for msg in meta_info.get('confirm_messages', []):
                 order.log_action('pretix.event.order.consent', data={'msg': msg})
+        if customer and customer_attached:
+            customer.log_action('pretix.customer.order.attached', data={'order': order.code})
 
     order_placed.send(event, order=order)
     return order, payments
@@ -981,9 +983,6 @@ def _perform_order(event: Event, payment_requests: List[dict], position_ids: Lis
         if not p['pprov']:
             raise OrderError(error_messages['internal'])
 
-    if customer:
-        customer = event.organizer.customers.get(pk=customer)
-
     if email == settings.PRETIX_EMAIL_NONE_VALUE:
         email = None
 
@@ -995,6 +994,30 @@ def _perform_order(event: Event, payment_requests: List[dict], position_ids: Lis
         except InvoiceAddress.DoesNotExist:
             pass
 
+    customer_attached = False
+    if customer:
+        customer = event.organizer.customers.get(pk=customer)
+    elif event.settings.customer_accounts_link_by_email in ('attach', 'create') and email:
+        try:
+            customer = event.organizer.customers.get(email__iexact=email)
+            customer_attached = True
+        except Customer.MultipleObjectsReturned:
+            logger.warning(f'Multiple customer accounts found for {email}, not attaching.')
+        except Customer.DoesNotExist:
+            if event.settings.customer_accounts_link_by_email == 'create':
+                customer = event.organizer.customers.create(
+                    email=email,
+                    name_parts=addr.name_parts if addr else None,
+                    phone=(meta_info or {}).get('contact_form_data', {}).get('phone'),
+                    is_active=True,
+                    is_verified=False,
+                    locale=locale,
+                )
+                customer.set_unusable_password()
+                customer.save()
+                customer.log_action('pretix.customer.created.auto', {})
+                customer_attached = True
+
     requires_seat = Exists(
         SeatCategoryMapping.objects.filter(
             Q(product=OuterRef('item'))
@@ -1018,7 +1041,7 @@ def _perform_order(event: Event, payment_requests: List[dict], position_ids: Lis
         locale=locale,
         invoice_address=addr,
         meta_info=meta_info,
-        customer=customer,
+        customer=customer if not customer_attached else None,
     )
 
     lockfn = NoLockManager
@@ -1041,10 +1064,11 @@ def _perform_order(event: Event, payment_requests: List[dict], position_ids: Lis
             raise OrderError(error_messages['empty'])
         if len(position_ids) != len(positions):
             raise OrderError(error_messages['internal'])
-        _check_positions(event, now_dt, positions, address=addr, sales_channel=sales_channel, customer=customer)
+        _check_positions(event, now_dt, positions, address=addr, sales_channel=sales_channel,
+                         customer=customer if not customer_attached else None)
         order, payment_objs = _create_order(event, email, positions, now_dt, payment_requests,
                                             locale=locale, address=addr, meta_info=meta_info, sales_channel=sales_channel,
-                                            shown_total=shown_total, customer=customer)
+                                            shown_total=shown_total, customer=customer, customer_attached=customer_attached)
         try:
             for p in payment_objs:
                 if p.provider == 'free':
diff --git a/src/pretix/base/settings.py b/src/pretix/base/settings.py
index 7518ddf685..35022034c9 100644
--- a/src/pretix/base/settings.py
+++ b/src/pretix/base/settings.py
@@ -159,13 +159,37 @@ DEFAULTS = {
     },
     'customer_accounts_link_by_email': {
         'default': 'False',
-        'type': bool,
-        'form_class': forms.BooleanField,
-        'serializer_class': serializers.BooleanField,
+        'type': str,
+        'form_class': forms.ChoiceField,
+        'serializer_class': serializers.ChoiceField,
+        'serializer_kwargs': dict(
+            choices=(
+                ('False', _('Keep guest orders separate and do not link them to customer accounts.')),
+                ('True', _('Do not attach guest orders to customer accounts, but show them in customer '
+                           'accounts with a verified matching email address.')),
+                ('attach', _('Attach guest orders to existing customer accounts with a matching email address if such '
+                             'an account exists.')),
+                ('create', _('Attach guest orders to existing customer accounts with a matching email and '
+                             'automatically create a customer account for all others.')),
+                ('forbidden', _('Do not allow guest orders.')),
+            ),
+        ),
         'form_kwargs': dict(
-            label=_("Match orders based on email address"),
-            help_text=_("This will allow registered customers to access orders made with the same email address, even if the customer "
-                        "was not logged in during the purchase.")
+            label=_("Guest order handling"),
+            widget=forms.RadioSelect,
+            choices=(
+                ('False', _('Keep guest orders separate and do not link them to customer accounts.')),
+                ('True', _('Do not attach guest orders to customer accounts, but show them in customer '
+                           'accounts with a verified matching email address.')),
+                ('attach', _('Attach guest orders to existing customer accounts with a matching email address if '
+                             'such an account exists.')),
+                ('create', _('Attach guest orders to existing customer accounts with a matching email address and '
+                             'automatically create a customer account for all others.')),
+                ('forbidden', _('Do not allow guest orders.')),
+            ),
+            help_text=_('Please be aware that creating customer accounts without a users consent might not be a '
+                        'good idea for privacy reasons in some jurisdictions or situations. We always recommend to '
+                        'let the user choose if they want an account.'),
         )
     },
     'max_items_per_order': {
diff --git a/src/pretix/control/logdisplay.py b/src/pretix/control/logdisplay.py
index 89b26e782a..c100d49b49 100644
--- a/src/pretix/control/logdisplay.py
+++ b/src/pretix/control/logdisplay.py
@@ -331,7 +331,10 @@ def pretixcontrol_logentry_display(sender: Event, logentry: LogEntry, **kwargs):
         'pretix.membershiptype.changed': _('The membership type has been changed.'),
         'pretix.membershiptype.deleted': _('The membership type has been deleted.'),
         'pretix.customer.created': _('The account has been created.'),
+        'pretix.customer.created.auto': _('The account has been automatically created during an order.'),
+        'pretix.customer.claimed': _('The automatically created account has been claimed by the customer.'),
         'pretix.customer.changed': _('The account has been changed.'),
+        'pretix.customer.order.attached': _('An order was automatically attached to the customer.'),
         'pretix.customer.membership.created': _('A membership for this account has been added.'),
         'pretix.customer.membership.changed': _('A membership of this account has been changed.'),
         'pretix.customer.membership.deleted': _('A membership of this account has been deleted.'),
diff --git a/src/pretix/control/templates/pretixcontrol/organizers/customers.html b/src/pretix/control/templates/pretixcontrol/organizers/customers.html
index 3bba675fcb..a3d9c283fe 100644
--- a/src/pretix/control/templates/pretixcontrol/organizers/customers.html
+++ b/src/pretix/control/templates/pretixcontrol/organizers/customers.html
@@ -79,9 +79,9 @@
                             </a>
                         </td>
                         <td>
-                            {% if not c.is_verified %}<strike>{% endif %}
+                            {% if not c.is_verified %}<span class="text-muted">{% endif %}
                             {{ c.email|default_if_none:"" }}
-                            {% if not c.is_verified %}</strike>{% endif %}
+                            {% if not c.is_verified %}</span>{% endif %}
                         </td>
                         <td>{{ c.name }}</td>
                         <td>{% if c.external_identifier %}{{ c.external_identifier }}{% endif %}</td>
diff --git a/src/pretix/control/views/organizer.py b/src/pretix/control/views/organizer.py
index d13c0a8413..f0839f5846 100644
--- a/src/pretix/control/views/organizer.py
+++ b/src/pretix/control/views/organizer.py
@@ -2215,9 +2215,9 @@ class CustomerDetailView(OrganizerDetailViewMixin, OrganizerPermissionRequiredMi
 
     def get_queryset(self):
         q = Q(customer=self.customer)
-        if self.request.organizer.settings.customer_accounts_link_by_email and self.customer.email:
+        if self.request.organizer.settings.customer_accounts_link_by_email == 'True' and self.customer.email:
             # This is safe because we only let customers with verified emails log in
-            q |= Q(email__iexact=self.customer.email)
+            q |= Q(customer__isnull=True, email__iexact=self.customer.email)
         qs = Order.objects.filter(
             q
         ).select_related('event').order_by('-datetime')
diff --git a/src/pretix/presale/checkoutflow.py b/src/pretix/presale/checkoutflow.py
index f40c8fced6..cbd3641754 100644
--- a/src/pretix/presale/checkoutflow.py
+++ b/src/pretix/presale/checkoutflow.py
@@ -269,7 +269,7 @@ class CustomerStep(CartMixin, TemplateFlowStep):
 
     @cached_property
     def guest_allowed(self):
-        return not any(
+        return self.request.event.settings.customer_accounts_link_by_email != 'forbidden' and not any(
             p.item.require_membership or
             (p.variation and p.variation.require_membership) or
             p.item.grant_membership_type_id
diff --git a/src/pretix/presale/forms/customer.py b/src/pretix/presale/forms/customer.py
index f3db3e8d8d..8c09d813f9 100644
--- a/src/pretix/presale/forms/customer.py
+++ b/src/pretix/presale/forms/customer.py
@@ -144,6 +144,7 @@ class RegistrationForm(forms.Form):
         self.standalone = kwargs.pop('standalone')
         self.signer = signing.TimestampSigner(salt=f'customer-registration-captcha-{get_client_ip(request)}')
         super().__init__(*args, **kwargs)
+        self.instance = None
 
         event = getattr(request, "event", None)
         if event and event.settings.order_phone_asked:
@@ -214,14 +215,17 @@ class RegistrationForm(forms.Form):
 
         if email is not None:
             try:
-                self.request.organizer.customers.get(email=email.lower())
+                existing = self.request.organizer.customers.get(email=email.lower())
             except Customer.DoesNotExist:
                 pass
             else:
-                raise forms.ValidationError(
-                    {'email': self.error_messages['duplicate']},
-                    code='duplicate',
-                )
+                if not existing.is_active or existing.is_verified or existing.has_usable_password():
+                    raise forms.ValidationError(
+                        {'email': self.error_messages['duplicate']},
+                        code='duplicate',
+                    )
+                else:
+                    self.instance = existing
 
         if self.standalone:
             expect = -1
@@ -256,19 +260,29 @@ class RegistrationForm(forms.Form):
         return self.cleaned_data
 
     def create(self):
-        customer = self.request.organizer.customers.create(
-            email=self.cleaned_data['email'],
-            name_parts=self.cleaned_data['name_parts'],
-            phone=self.cleaned_data.get('phone'),
-            is_active=True,
-            is_verified=False,
-            locale=get_language_without_region(),
-        )
-        customer.set_unusable_password()
-        customer.save()
-        customer.log_action('pretix.customer.created', {})
-        customer.send_activation_mail()
-        return customer
+        if self.instance:
+            self.instance.name_parts = self.cleaned_data['name_parts']
+            if self.cleaned_data.get('phone'):
+                self.instance.phone = self.cleaned_data.get('phone')
+            self.instance.locale = get_language_without_region()
+            self.instance.save()
+            self.instance.log_action('pretix.customer.claimed', {})
+            self.instance.send_activation_mail()
+            return self.instance
+        else:
+            customer = self.request.organizer.customers.create(
+                email=self.cleaned_data['email'],
+                name_parts=self.cleaned_data['name_parts'],
+                phone=self.cleaned_data.get('phone'),
+                is_active=True,
+                is_verified=False,
+                locale=get_language_without_region(),
+            )
+            customer.set_unusable_password()
+            customer.save()
+            customer.log_action('pretix.customer.created', {})
+            customer.send_activation_mail()
+            return customer
 
 
 class SetPasswordForm(forms.Form):
diff --git a/src/pretix/presale/views/customer.py b/src/pretix/presale/views/customer.py
index 878e0de74e..eb041127fe 100644
--- a/src/pretix/presale/views/customer.py
+++ b/src/pretix/presale/views/customer.py
@@ -352,9 +352,9 @@ class ProfileView(CustomerRequiredMixin, ListView):
 
     def get_queryset(self):
         q = Q(customer=self.request.customer)
-        if self.request.organizer.settings.customer_accounts_link_by_email and self.request.customer.email:
+        if self.request.organizer.settings.customer_accounts_link_by_email == 'True' and self.request.customer.email:
             # This is safe because we only let customers with verified emails log in
-            q |= Q(email__iexact=self.request.customer.email)
+            q |= Q(customer__isnull=True, email__iexact=self.request.customer.email)
         qs = Order.objects.filter(
             q
         ).prefetch_related(
diff --git a/src/tests/presale/test_checkout.py b/src/tests/presale/test_checkout.py
index 02fa5ea97b..5501c9d113 100644
--- a/src/tests/presale/test_checkout.py
+++ b/src/tests/presale/test_checkout.py
@@ -4315,6 +4315,56 @@ class CustomerCheckoutTestCase(BaseCheckoutTestCase, TestCase):
         assert order.email == 'admin@localhost'
         assert not order.customer
 
+    def test_guest_not_allowed(self):
+        self.orga.settings.customer_accounts_link_by_email = 'forbidden'
+        response = self.client.get('/%s/%s/checkout/start' % (self.orga.slug, self.event.slug), follow=True)
+        self.assertRedirects(response, '/%s/%s/checkout/customer/' % (self.orga.slug, self.event.slug),
+                             target_status_code=200)
+
+        response = self.client.post('/%s/%s/checkout/customer/' % (self.orga.slug, self.event.slug), {
+            'customer_mode': 'guest'
+        }, follow=True)
+        self.assertEqual(response.status_code, 200)
+
+    def test_guest_attach(self):
+        self.orga.settings.customer_accounts_link_by_email = 'attach'
+        response = self.client.get('/%s/%s/checkout/start' % (self.orga.slug, self.event.slug), follow=True)
+        self.assertRedirects(response, '/%s/%s/checkout/customer/' % (self.orga.slug, self.event.slug),
+                             target_status_code=200)
+
+        self.client.post('/%s/%s/checkout/customer/' % (self.orga.slug, self.event.slug), {
+            'customer_mode': 'guest'
+        }, follow=True)
+        self.client.post('/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug), {
+            'email': 'john@example.org'
+        }, follow=True)
+
+        order = self._finish()
+        assert order.email == 'john@example.org'
+        assert order.customer == self.customer
+
+    def test_guest_create(self):
+        self.orga.settings.customer_accounts_link_by_email = 'create'
+        response = self.client.get('/%s/%s/checkout/start' % (self.orga.slug, self.event.slug), follow=True)
+        self.assertRedirects(response, '/%s/%s/checkout/customer/' % (self.orga.slug, self.event.slug),
+                             target_status_code=200)
+
+        self.client.post('/%s/%s/checkout/customer/' % (self.orga.slug, self.event.slug), {
+            'customer_mode': 'guest'
+        }, follow=True)
+        self.client.post('/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug), {
+            'email': 'jack@example.org'
+        }, follow=True)
+
+        order = self._finish()
+        assert order.email == 'jack@example.org'
+        assert order.customer
+        c = order.customer
+        assert c.email == order.email
+        assert not c.has_usable_password()
+        assert c.is_active
+        assert not c.is_verified
+
     def test_guest_even_if_logged_in(self):
         self.client.post('/%s/account/login' % self.orga.slug, {
             'email': 'john@example.org',
@@ -4410,6 +4460,24 @@ class CustomerCheckoutTestCase(BaseCheckoutTestCase, TestCase):
         assert response.status_code == 200
         assert b'alert-danger' in response.content
 
+    def test_register_valid_account_previously_autocrated(self):
+        with scopes_disabled():
+            c = self.orga.customers.create(email='foo@example.com', is_active=True, is_verified=False)
+            c.set_unusable_password()
+            c.save()
+        response = self.client.get('/%s/%s/checkout/start' % (self.orga.slug, self.event.slug), follow=True)
+        self.assertRedirects(response, '/%s/%s/checkout/customer/' % (self.orga.slug, self.event.slug),
+                             target_status_code=200)
+
+        response = self.client.post('/%s/%s/checkout/customer/' % (self.orga.slug, self.event.slug), {
+            'customer_mode': 'register',
+            'register-email': 'foo@example.com',
+            'register-name_parts_0': 'John Doe',
+        }, follow=False)
+        self.assertRedirects(response, '/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug),
+                             target_status_code=200)
+        assert len(djmail.outbox) == 1
+
     def test_register_valid(self):
         response = self.client.get('/%s/%s/checkout/start' % (self.orga.slug, self.event.slug), follow=True)
         self.assertRedirects(response, '/%s/%s/checkout/customer/' % (self.orga.slug, self.event.slug),
diff --git a/src/tests/presale/test_customer.py b/src/tests/presale/test_customer.py
index c267d18c99..16a96d44b9 100644
--- a/src/tests/presale/test_customer.py
+++ b/src/tests/presale/test_customer.py
@@ -124,16 +124,40 @@ def test_org_register(env, client):
 
 @pytest.mark.django_db
 def test_org_register_duplicate_email(env, client):
+    signer = signing.TimestampSigner(salt='customer-registration-captcha-127.0.0.1')
     with scopes_disabled():
         env[0].customers.create(email='john@example.org')
     r = client.post('/bigevents/account/register', {
         'email': 'john@example.org',
         'name_parts_0': 'John Doe',
-    })
+        'challenge': signer.sign('1+2'),
+        'response': '3',
+    }, REMOTE_ADDR='127.0.0.1')
     assert b'already registered' in r.content
     assert r.status_code == 200
 
 
+@pytest.mark.django_db
+def test_org_register_duplicate_email_ignored_if_previously_autocreated(env, client):
+    signer = signing.TimestampSigner(salt='customer-registration-captcha-127.0.0.1')
+    with scopes_disabled():
+        c = env[0].customers.create(email='john@example.org', is_active=True, is_verified=False)
+        c.set_unusable_password()
+        c.save()
+    r = client.post('/bigevents/account/register', {
+        'email': 'john@example.org',
+        'name_parts_0': 'John Doe',
+        'challenge': signer.sign('1+2'),
+        'response': '3',
+    }, REMOTE_ADDR='127.0.0.1')
+    assert r.status_code == 302
+    assert len(djmail.outbox) == 1
+    with scopes_disabled():
+        customer = env[0].customers.get(email='john@example.org')
+        assert not customer.is_verified
+        assert customer.is_active
+
+
 @pytest.mark.django_db
 def test_org_resetpw(env, client):
     with scopes_disabled():
@@ -479,7 +503,7 @@ def test_org_order_list(env, client):
     assert o2.code not in content
     assert o3.code in content
 
-    env[0].settings.customer_accounts_link_by_email = True
+    env[0].settings.customer_accounts_link_by_email = 'True'
 
     r = client.get('/bigevents/account/')
     assert r.status_code == 200