diff --git a/.env.example b/.env.example
index 3585dbf6..e4b61749 100644
--- a/.env.example
+++ b/.env.example
@@ -39,6 +39,11 @@ EMAIL_FROM=noreply@yourdomain.com
 FRONTEND_URL=https://yourdomain.com
 ADMIN_URL=https://yourdomain.com
 
+# API URL for email assets (logos, images in notification emails)
+# This must be the publicly accessible URL where email recipients can load images.
+# If not set, defaults to http://localhost:3001 which will show broken images in emails.
+API_URL=https://yourdomain.com/api
+
 # Frontend API base
 # For pre-built images and production behind a reverse proxy, keep '/api'.
 # If you rebuild the frontend yourself, you may set a full URL at build time.
diff --git a/backend/.env.example b/backend/.env.example
index b9ca6155..fb1ce982 100644
--- a/backend/.env.example
+++ b/backend/.env.example
@@ -14,6 +14,11 @@ ADMIN_URL=https://photos.example.com
 FRONTEND_URL=https://photos.example.com
 BACKEND_URL=https://photos.example.com  # Or https://api.photos.example.com if separate
 
+# API URL for email assets (logos, images in emails)
+# This must be the publicly accessible URL where recipients can load images
+# If not set, defaults to http://localhost:3001 which will break images in production emails
+API_URL=https://photos.example.com/api
+
 # Database Configuration
 DATABASE_CLIENT=pg
 DB_HOST=localhost