Make Synapse use ma1sd (if enabled) for threepid registration

roles/matrix-synapse/defaults/main.yml

@@ -164,6 +164,14 @@ matrix_synapse_enable_group_creation: false
 # A list of 3PID types which users must supply when registering (possible values: email, msisdn).
 matrix_synapse_registrations_require_3pid: []
 
+# The server to use for email threepid validation. When empty, Synapse does it by itself.
+# Otherwise, this should be pointed to an identity server.
+matrix_synapse_account_threepid_delegates_email: ''
+
+# The server to use for phone number threepid validation. When empty, validation cannot happen, as Synapse doesn't support it.
+# To make it work, this should be pointed to an identity server.
+matrix_synapse_account_threepid_delegates_msisdn: ''
+
 # Users who register on this homeserver will automatically be joined to these rooms.
 # Rooms are to be specified using addresses (e.g. `#address:example.com`)
 matrix_synapse_auto_join_rooms: []

roles/matrix-synapse/templates/synapse/homeserver.yaml.j2

@@ -1060,8 +1060,8 @@ trusted_third_party_id_servers:
 # If a delegate is specified, the config option public_baseurl must also be filled out.
 #
 account_threepid_delegates:
-    #email: https://example.com     # Delegate email sending to example.com
-    #msisdn: http://localhost:8090  # Delegate SMS sending to this local process
+    email: {{ matrix_synapse_account_threepid_delegates_email|to_json }}
+    msisdn: {{ matrix_synapse_account_threepid_delegates_msisdn|to_json }}
 
 # Users who register on this homeserver will automatically be joined
 # to these rooms