diff --git a/zerver/migrations/0325_fix_user_dummy_emails.py b/zerver/migrations/0325_fix_user_dummy_emails.py
new file mode 100644
index 0000000000..320bf751b2
--- /dev/null
+++ b/zerver/migrations/0325_fix_user_dummy_emails.py
@@ -0,0 +1,86 @@
+from typing import Any
+
+from django.conf import settings
+from django.core.validators import ValidationError, validate_email
+from django.db import migrations, transaction
+from django.db.backends.postgresql.schema import DatabaseSchemaEditor
+from django.db.migrations.state import StateApps
+
+# The helper functions below are taken from models.py
+# without any functional changes, they're just a workaround
+# for the lack of access to Realm methods in migrations.
+
+
+def host_for_subdomain(subdomain: str) -> str:
+    if subdomain == "":
+        return settings.EXTERNAL_HOST
+    default_host = f"{subdomain}.{settings.EXTERNAL_HOST}"
+    return settings.REALM_HOSTS.get(subdomain, default_host)
+
+
+def get_realm_host(realm: Any) -> str:
+    return host_for_subdomain(realm.string_id)
+
+
+def get_fake_email_domain(realm: Any) -> str:
+    try:
+        # Check that realm.host can be used to form valid email addresses.
+        host = get_realm_host(realm)
+        validate_email(f"bot@{host}")
+        return host
+    except ValidationError:
+        pass
+
+    try:
+        # Check that the fake email domain can be used to form valid email addresses.
+        validate_email("bot@" + settings.FAKE_EMAIL_DOMAIN)
+    except ValidationError:
+        raise Exception(
+            settings.FAKE_EMAIL_DOMAIN + " is not a valid domain. "
+            "Consider setting the FAKE_EMAIL_DOMAIN setting."
+        )
+
+    return settings.FAKE_EMAIL_DOMAIN
+
+
+def fix_user_emails(apps: StateApps, schema_editor: DatabaseSchemaEditor) -> None:
+    EMAIL_ADDRESS_VISIBILITY_EVERYONE = 1
+    UserProfile = apps.get_model("zerver", "UserProfile")
+
+    BATCH_SIZE = 200
+    last_id = 0
+    while True:
+        with transaction.atomic():
+            user_profiles = list(
+                UserProfile.objects.exclude(
+                    realm__email_address_visibility=EMAIL_ADDRESS_VISIBILITY_EVERYONE
+                )
+                .filter(
+                    email__iregex=r"^user\d+" + f"@{settings.FAKE_EMAIL_DOMAIN}$", id__gt=last_id
+                )
+                .select_for_update()
+                .order_by("id")[:BATCH_SIZE]
+            )
+            if not user_profiles:
+                # Nothing left to fix.
+                break
+            last_id = user_profiles[-1].id
+
+            for user_profile in user_profiles:
+                user_profile.email = (
+                    f"user{user_profile.id}@{get_fake_email_domain(user_profile.realm)}"
+                )
+
+            UserProfile.objects.bulk_update(user_profiles, ["email"])
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    dependencies = [
+        ("zerver", "0324_fix_deletion_cascade_behavior"),
+    ]
+
+    operations = [
+        migrations.RunPython(fix_user_emails, reverse_code=migrations.RunPython.noop),
+    ]