--- a/dovecot-example.conf	Mon Aug 06 17:45:25 2007 +0300
+++ b/dovecot-example.conf	Mon Aug 06 18:02:48 2007 +0300
@@ -720,6 +720,8 @@
 # user's previous authentication was successful, but this one wasn't, the
 # cache isn't used. For now this works only with plaintext authentication.
 #auth_cache_ttl = 3600
+# TTL for negative hits (user not found). 0 disables caching them completely.
+#auth_cache_negative_ttl = 3600
 
 # Space separated list of realms for SASL authentication mechanisms that need
 # them. You can leave it empty if you don't want to support multiple realms.