diff --git a/backend/main.go b/backend/main.go
index 0d3ad68dc..350b45bed 100644
--- a/backend/main.go
+++ b/backend/main.go
@@ -38,7 +38,7 @@ func main() {
 
 	modules := initModules(db, cfg)
 
-	adminEmail := env.String("UTMSTACK_ADMIN_EMAIL", "admin@localhost", false)
+	adminEmail := env.String("UTMSTACK_ADMIN_EMAIL", "admin", false)
 	created, err := modules.tenant.GetBootstrapUsecase().EnsureDefaultTenant(
 		appCtx, adminEmail, env.String("UTMSTACK_ADMIN_PASSWORD", "", false))
 	if err != nil {
diff --git a/frontend/src/features/onboarding/AdminSetupGate.tsx b/frontend/src/features/onboarding/AdminSetupGate.tsx
index 27ddde6e8..7179e683a 100644
--- a/frontend/src/features/onboarding/AdminSetupGate.tsx
+++ b/frontend/src/features/onboarding/AdminSetupGate.tsx
@@ -8,9 +8,9 @@ import { Input } from '@/shared/components/ui/input'
 import { IS_FEDERATION } from '@/shared/config/mode'
 import { useAuth } from '@/features/auth'
 
-// The seeded admin ships with this placeholder address; treat it (and an empty
+// The seeded admin ships with the placeholder "admin"; treat it (and an empty
 // email) as "not configured yet".
-const DEFAULT_ADMIN_EMAIL = 'admin@localhost'
+const DEFAULT_ADMIN_EMAIL = 'admin'
 
 function needsAdminEmail(email: string | undefined): boolean {
   const e = (email ?? '').trim().toLowerCase()
@@ -21,7 +21,7 @@ const EMAIL_RE = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
 
 /**
  * First-run blocking gate (ported from v11): an admin still on the default email
- * (admin@localhost) must set a real address before using the app — password
+ * ("admin") must set a real address before using the app — password
  * reset, notifications, alert emails and threat-intel registration all depend on
  * it. The modal can't be dismissed; after saving, the admin is guided to the
  * mail-server settings (non-blocking). Instance mode only — the federation
diff --git a/installer/services/postgres.go b/installer/services/postgres.go
index 8a643f01f..d963c367a 100644
--- a/installer/services/postgres.go
+++ b/installer/services/postgres.go
@@ -69,13 +69,13 @@ func GetAdminEmail() (string, error) {
 	containerID := containerIDs[0]
 
 	// The instance's administrator: the platform tenant's oldest active admin.
-	// "admin@localhost" is the placeholder the backend creates when nobody
-	// supplied an address, so it is not an answer.
+	// "admin" is the placeholder the backend creates when nobody supplied an
+	// address, so it is not an answer.
 	query := `SELECT u.email FROM "user" u ` +
 		`JOIN user_role ur ON ur.user_id = u.id ` +
 		`JOIN role r ON r.id = ur.role_id AND r.name = 'ROLE_ADMIN' ` +
 		`WHERE u.tenant_id = '` + defaultTenantID + `' ` +
-		`AND u.status = 'active' AND u.email <> 'admin@localhost' ` +
+		`AND u.status = 'active' AND u.email <> 'admin' ` +
 		`ORDER BY u.created_at LIMIT 1`
 	output, err := utils.RunCmdWithOutput("docker", "exec", containerID, "psql", "-U", "postgres", "-d", "utmstack", "-t", "-c", query)
 	if err != nil {