Show domain part of message-id sorted by popularity.

pg/top-message-ids.sql

@@ -0,0 +1,12 @@
+SELECT
+    COUNT(value),
+    LOWER(COALESCE(SUBSTRING(value from '.*@(.*)>'), value)) AS id
+FROM
+    header
+WHERE
+    name = 'Message-Id'
+GROUP BY
+    id
+ORDER BY
+    count DESC
+;