diff --git a/server/plugins-available/maildrop_plugin.inc.php b/server/plugins-available/maildrop_plugin.inc.php
index 0c806ab24200a099c9fb7404b8e1a3af8197a282..998b7c4cbedf8ee3ad0bd9d835e0131ad709c369 100644
--- a/server/plugins-available/maildrop_plugin.inc.php
+++ b/server/plugins-available/maildrop_plugin.inc.php
@@ -196,6 +196,9 @@ class maildrop_plugin {
 					}
 					$mailfilter_content .= $data["new"]["custom_mailfilter"];
 					
+					// Replace windows linebreaks in mailfilter file
+					$mailfilter_content = str_replace("\r\n","\n",$mailfilter_content);
+					
 					file_put_contents($config_file_path,$mailfilter_content);
 					$app->log("Writing new custom Mailfiter".$config_file_path,LOGLEVEL_DEBUG);
 					chmod($config_file_path, 0770);