diff --git a/modules/mailu/module.json b/modules/mailu/module.json
index 4ba4d89..a868ff7 100644
--- a/modules/mailu/module.json
+++ b/modules/mailu/module.json
@@ -1,6 +1,10 @@
 {
   "module": "mailu",
   "version": "1",
+  "upgrade": {
+    "policy": "record",
+    "why": "people's mail: any change to how its containers are declared recreates them together in one send, and the mail is down for everyone until they are up again — a person chooses the moment (hq ADR 0242, issue 294)"
+  },
   "capabilities": [
     "container-runtime"
   ],