Add sender rewriting scheme (SRS).

mail_system/tasks/database.yml

@@ -146,6 +146,7 @@
     - t timestamp default now()
     - original varchar(250) not null
     - rewritten varchar(250) not null
+    - srs_id bigint
 
 - name: database index mail_from__rewritten
   postgresql_idx:
@@ -158,3 +159,15 @@
     table: mail_from
     columns: rewritten
     idxname: mail_from__rewritten
+
+- name: database index mail_from__srs_id
+  postgresql_idx:
+    login_host: "{{ mailserver.postgresql.host }}"
+    port: "{{ mailserver.postgresql.port }}"
+    login_user: "{{ mailserver.postgresql.username }}"
+    login_password: "{{ mailserver.postgresql.password }}"
+    db: "{{ mailserver.postgresql.dbname }}"
+    ssl_mode: disable
+    table: mail_from
+    columns: srs_id
+    idxname: mail_from__srs_id