diff --git a/mailserver.env b/mailserver.env
index 49bc2cca..9b085c9f 100644
--- a/mailserver.env
+++ b/mailserver.env
@@ -401,7 +401,10 @@ SA_TAG2=6.31
 SA_KILL=10.0
 
 # add tag to subject if spam detected
-SA_SPAM_SUBJECT='***SPAM*** '
+# The value `undef` opts-out of this feature. The value shown below is the default.
+# NOTE: By default spam is delivered to a junk folder, reducing the value of adding a subject prefix.
+# NOTE: If not using Docker Compose, other CRI may require the single quotes removed.
+#SA_SPAM_SUBJECT='***SPAM*** '
 
 # -----------------------------------------------
 # --- Fetchmail Section -------------------------