Merge pull request #4915 from twesterhever/temp-freemail-mdn

Add detection for freemail and disposable e-mail usage for message delivery notification

conf/composites.conf

@@ -165,12 +165,19 @@ composites {
     group = "scams";
   }
   FREEMAIL_AFF {
-    expression = "(FREEMAIL_FROM | FREEMAIL_ENVFROM | FREEMAIL_REPLYTO) & (TO_DN_RECIPIENTS | R_UNDISC_RCPT) & (INTRODUCTION | FROM_NAME_HAS_TITLE | FREEMAIL_REPLYTO_NEQ_FROM_DOM | SUBJECT_HAS_CURRENCY)";
+    expression = "(FREEMAIL_FROM | FREEMAIL_ENVFROM | FREEMAIL_REPLYTO | FREEMAIL_MDN) & (TO_DN_RECIPIENTS | R_UNDISC_RCPT) & (INTRODUCTION | FROM_NAME_HAS_TITLE | FREEMAIL_REPLYTO_NEQ_FROM_DOM | SUBJECT_HAS_CURRENCY)";
     score = 4.0;
     policy = "leave";
     description = "Message exhibits strong characteristics of advance fee fraud (AFF a/k/a '419' spam) involving freemail addresses";
     group = "scams";
   }
+  SUSPICIOUS_MDN {
+    expression = "(FREEMAIL_MDN | DISPOSABLE_MDN) & !(FREEMAIL_FROM | FREEMAIL_ENVFROM)";
+    score = 2.0;
+    policy = "leave";
+    description = "Message delivery notification should go to freemail or disposable e-mail, but message was not sent from a freemail address";
+    group = "scams";
+  }
   REDIRECTOR_URL_ONLY {
     expression = "HFILTER_URL_ONLY & REDIRECTOR_URL";
     score = 1.0;

conf/modules.d/multimap.conf

@@ -85,6 +85,16 @@ multimap {
     score = 0.0;
   }
 
+  freemail_mdn {
+    type = "header";
+    header = "Disposition-Notification-To";
+    filter = "email:domain";
+    map = "https://maps.rspamd.com/freemail/free.txt.zst";
+    symbol = "FREEMAIL_MDN";
+    description = "Disposition-Notification-To is a Freemail address";
+    score = 0.0;
+  }
+
   # Disposable Addresses
   disposable_envfrom {
     type = "from";
@@ -147,6 +157,16 @@ multimap {
     score = 0.0;
   }
 
+  disposable_mdn {
+    type = "header";
+    header = "Disposition-Notification-To";
+    filter = "email:domain";
+    map = "https://maps.rspamd.com/freemail/disposable.txt.zst";
+    symbol = "DISPOSABLE_MDN";
+    description = "Disposition-Notification-To is a disposable e-mail address";
+    score = 0.5;
+  }
+
   .include(try=true,priority=5) "${DBDIR}/dynamic/multimap.conf"
   .include(try=true,priority=1,duplicate=merge) "$LOCAL_CONFDIR/local.d/multimap.conf"
   .include(try=true,priority=10) "$LOCAL_CONFDIR/override.d/multimap.conf"