refer links induce inbox spam

modules/message/src/main/Api.scala

@@ -50,7 +50,7 @@ final class Api(
           text = data.text,
           creatorId = me.id,
           invitedId = data.user.id) |> { t =>
-            val thread = me.troll.fold(t deleteFor invited, t)
+            val thread = Automute(s"${data.subject} ${data.text}", me).fold(t deleteFor invited, t)
             sendUnlessBlocked(thread, fromMod) >>-
               updateUser(invited) >>- {
                 val text = s"${data.subject} ${data.text}"

modules/message/src/main/Automute.scala

@@ -0,0 +1,16 @@
+package lila.message
+
+private object Automute {
+
+  def apply(text: String, by: lila.user.User) = by.troll || scan(text)
+
+  private def scan(text: String) = blacklist exists text.contains
+
+  private val blacklist = List(
+    /* While links to other chess websites are welcome,
+     * refer links grant the referrer money,
+     * effectively inducing spam */
+    "velocitychess.com/ref/",
+    "chess24.com?ref="
+  )
+}