diff --git a/.envrc.sample b/.envrc.sample
index a94c4d6..5f75635 100644
--- a/.envrc.sample
+++ b/.envrc.sample
@@ -10,3 +10,5 @@ export LETS_ENCRYPT_ENV=production
 
 # $DOMAIN will be added by default, specify any more here:
 #export EXTRA_SENDER_DOMAINS="app.example.com"
+# Replace *.example.com with example.com in outgoing mail
+#export MASQUERADED_DOMAINS="example.com"
diff --git a/compose.yml b/compose.yml
index 2dd776f..7cd52fc 100644
--- a/compose.yml
+++ b/compose.yml
@@ -19,6 +19,7 @@ services:
       INBOUND_DEBUGGING: "${INBOUND_DEBUGGING:-0}"
       ALLOWED_SENDER_DOMAINS: "${EXTRA_SENDER_DOMAINS} ${DOMAIN}"
       POSTFIX_myhostname: "${DOMAIN}"
+      MASQUERADED_DOMAINS: "${MASQUERADED_DOMAINS}"
     deploy:
       restart_policy:
         condition: on-failure