diff --git a/account/admin.py b/account/admin.py
index d6e28b4..bb74f79 100644
--- a/account/admin.py
+++ b/account/admin.py
@@ -35,7 +35,7 @@ class Meta:
 
 
 class MailingListAdmin(DisableDeleteAdminMixin, DisableAddAdminMixin, admin.ModelAdmin):
-    list_display = ("result", "csv_emails")
+    list_display = ("result", "number_of_emails")
 
     readonly_fields = ("result",)
     form = MailingListAdminForm
diff --git a/account/api/views.py b/account/api/views.py
index 94c94e5..9ebb5ae 100644
--- a/account/api/views.py
+++ b/account/api/views.py
@@ -1,6 +1,7 @@
 from django import db
 from django.core.exceptions import ValidationError
 from django.core.validators import validate_email
+from django.db.utils import IntegrityError
 from drf_spectacular.utils import extend_schema, OpenApiResponse
 from rest_framework import status, viewsets
 from rest_framework.decorators import action
@@ -93,8 +94,7 @@ def subscribe(self, request):
         email = request.data.get("email", None)
         if not email:
             return Response("No 'email' provided", status=status.HTTP_400_BAD_REQUEST)
-        if MailingListEmail.objects.filter(email=email).count() > 0:
-            return Response("'email' exists", status=status.HTTP_400_BAD_REQUEST)
+
         try:
             validate_email(email)
         except ValidationError as e:
@@ -103,8 +103,13 @@ def subscribe(self, request):
         if not mailing_list:
             # In case mailing list is not created for the result, it is created.
             mailing_list = MailingList.objects.create(result=result)
-
-        MailingListEmail.objects.create(mailing_list=mailing_list, email=email)
+        try:
+            MailingListEmail.objects.create(mailing_list=mailing_list, email=email)
+        except IntegrityError:
+            return Response(
+                "'email' and 'result' must be jointly null",
+                status=status.HTTP_400_BAD_REQUEST,
+            )
         user.has_subscribed = True
         user.save()
         return Response("subscribed", status=status.HTTP_201_CREATED)
diff --git a/account/migrations/0015_email_and_mailing_list_jointly_unique.py b/account/migrations/0015_email_and_mailing_list_jointly_unique.py
new file mode 100644
index 0000000..8e913dd
--- /dev/null
+++ b/account/migrations/0015_email_and_mailing_list_jointly_unique.py
@@ -0,0 +1,25 @@
+# Generated by Django 4.1.13 on 2024-04-30 07:25
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("account", "0014_remove_profile_is_filled_for_fun"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="mailinglistemail",
+            name="email",
+            field=models.EmailField(max_length=254),
+        ),
+        migrations.AddConstraint(
+            model_name="mailinglistemail",
+            constraint=models.UniqueConstraint(
+                fields=("email", "mailing_list"),
+                name="email_and_mailing_list_must_be_jointly:unique",
+            ),
+        ),
+    ]
diff --git a/account/models.py b/account/models.py
index 50a8ba8..fc994b3 100644
--- a/account/models.py
+++ b/account/models.py
@@ -72,12 +72,23 @@ def __str__(self):
     def csv_emails(self):
         return ",".join([e.email for e in self.emails.all()])
 
+    def number_of_emails(self):
+        return self.emails.count()
+
 
 class MailingListEmail(models.Model):
-    email = models.EmailField(unique=True)
+    email = models.EmailField()
     mailing_list = models.ForeignKey(
         MailingList, related_name="emails", on_delete=models.CASCADE
     )
 
     def __str__(self):
-        return self.email
+        return f"{self.email} {self.mailing_list}"
+
+    class Meta:
+        constraints = [
+            models.UniqueConstraint(
+                fields=["email", "mailing_list"],
+                name="email_and_mailing_list_must_be_jointly:unique",
+            )
+        ]
diff --git a/account/tests/test_api.py b/account/tests/test_api.py
index c0a4b05..4ddf6af 100644
--- a/account/tests/test_api.py
+++ b/account/tests/test_api.py
@@ -374,3 +374,34 @@ def test_mailing_list_unsubscribe_email_not_provided(
     url = reverse("account:profiles-unsubscribe")
     response = api_client_with_custom_ip_address.post(url)
     assert response.status_code == 400
+
+
+@pytest.mark.django_db
+@pytest.mark.parametrize(
+    "ip_address",
+    [
+        ("100.19.91.40"),
+    ],
+)
+def test_mailing_list_unique_constraints(api_client_with_custom_ip_address, users):
+    url = reverse("account:profiles-subscribe")
+    user = users.get(username="test1")
+    response = api_client_with_custom_ip_address.post(
+        url, {"email": "test@test.com", "user": user.id}
+    )
+    assert response.status_code == 201
+    assert MailingListEmail.objects.count() == 1
+    # Subscribed as the result (MailingList) is different than for user 'test1'
+    user = users.get(username="test2")
+    response = api_client_with_custom_ip_address.post(
+        url, {"email": "test@test.com", "user": user.id}
+    )
+    assert response.status_code == 201
+    assert MailingListEmail.objects.count() == 2
+    # Fails, as the email and result are not jointly unique.
+    user = users.get(username="test3")
+    response = api_client_with_custom_ip_address.post(
+        url, {"email": "test@test.com", "user": user.id}
+    )
+    assert response.status_code == 400
+    assert MailingListEmail.objects.count() == 2