diff --git a/mailserver.env b/mailserver.env
index fca74c8a..f2042651 100644
--- a/mailserver.env
+++ b/mailserver.env
@@ -341,7 +341,7 @@ POSTGREY_DELAY=300
 # delete entries older than N days since the last time that they have been seen
 POSTGREY_MAX_AGE=35
 # response when a mail is greylisted
-POSTGREY_TEXT=Delayed by Postgrey
+"POSTGREY_TEXT=Delayed by Postgrey"
 # whitelist host after N successful deliveries (N=0 to disable whitelisting)
 POSTGREY_AUTO_WHITELIST_CLIENTS=5