diff --git a/config/filter.d/postfix-sasl.conf b/config/filter.d/postfix-sasl.conf
index 35b064d3..e038b695 100644
--- a/config/filter.d/postfix-sasl.conf
+++ b/config/filter.d/postfix-sasl.conf
@@ -9,7 +9,7 @@ before = common.conf
 
 _daemon = postfix/(submission/)?smtp(d|s)
 
-failregex = ^%(__prefix_line)swarning: [-._\w]+\[<HOST>\]: SASL (?:LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed(: [ A-Za-z0-9+/]*={0,2})?\s*$
+failregex = ^%(__prefix_line)swarning: [-._\w]+\[<HOST>\]: SASL ((?i)LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed(: [ A-Za-z0-9+/]*={0,2})?\s*$
 
 ignoreregex =