[Rspamd] Create bad header map

data/conf/rspamd/custom/bulk_header.map

@@ -17,3 +17,4 @@
 /.*light-house-traffic.*/i
 /.*newsletterplus.*/i
 /.*X-Chpo.*/i
+/Thread-Topic:\s[a-zA-Z]{3}\s[a-zA-Z]{2}\s*$/i

data/conf/rspamd/local.d/groups.conf

@@ -9,6 +9,9 @@ symbols {
   "BAD_REP_POLICIES" {
     score = 2.0;
   }
+  "BAD_HEADER" {
+    score = 10.0;
+  }
   "BULK_HEADER" {
     score = 4.0;
   }

data/conf/rspamd/local.d/multimap.conf

@@ -19,6 +19,14 @@ BULK_HEADER {
   symbols_set = ["BULK_HEADER"];
 }
 
+BAD_HEADER {
+  type = "content";
+  map = "${LOCAL_CONFDIR}/custom/bad_header.map";
+  filter = "headers"
+  regexp = true;
+  symbols_set = ["BAD_HEADER"];
+}
+
 LOCAL_BL_ASN {
   require_symbols = "!MAILCOW_WHITE";
   type = "asn";