diff --git a/nuc/protonmail-bridge/docker-compose.yml b/nuc/protonmail-bridge/docker-compose.yml
index bb0449d..6ebc5cd 100644
--- a/nuc/protonmail-bridge/docker-compose.yml
+++ b/nuc/protonmail-bridge/docker-compose.yml
@@ -8,3 +8,7 @@ services:
     ports:
       - "1025:25/tcp"  # SMTP port
     restart: unless-stopped
+
+volumes:
+  protonmail:
+    external: true