diff --git a/users/migrations/0090_auto_20200418_0206.py b/users/migrations/0090_auto_20200418_0206.py
new file mode 100644
index 00000000..f5153b30
--- /dev/null
+++ b/users/migrations/0090_auto_20200418_0206.py
@@ -0,0 +1,35 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.28 on 2020-04-18 00:06
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+from django.db.models import Count
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('users', '0089_auto_20200418_0112'),
+    ]
+
+
+    def remove_double_email_accounts(apps, schema_editor):
+        db_alias = schema_editor.connection.alias
+        users = apps.get_model("users", "User")
+        duplicates = users.objects.using(db_alias).values('email').annotate(email_count=Count('email')).filter(email_count__gt=1)
+        for email_item in duplicates:
+            duplicate_users = users.objects.using(db_alias).filter(email=email_item['email']).order_by('last_login', 'registered')
+            for user in duplicate_users[1:]:
+                user.email=None
+                user.save()
+
+    def revert_remove_double_email_accounts(apps, schema_editor):
+        return
+
+    operations = [
+        migrations.RunPython(remove_double_email_accounts, revert_remove_double_email_accounts),
+        migrations.AlterField(
+            model_name='user',
+            name='email',
+            field=models.EmailField(blank=True, help_text='External email address allowing us to contact you.', max_length=254, null=True, unique=True),
+        ),
+    ]
diff --git a/users/models.py b/users/models.py
index 621617c3..1959219c 100755
--- a/users/models.py
+++ b/users/models.py
@@ -207,6 +207,7 @@ class User(
     email = models.EmailField(
         blank=True,
         null=True,
+        unique=True,
         help_text=_("External email address allowing us to contact you."),
     )
     local_email_redirect = models.BooleanField(