diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index 896159394c..10664ae8f7 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -54,15 +54,16 @@ pid_file: DATADIR/homeserver.pid
#
#require_auth_for_profile_requests: true
-# If set to 'false', requires authentication to access the server's public rooms
-# directory through the client API. Defaults to 'true'.
+# If set to 'true', removes the need for authentication to access the server's
+# public rooms directory through the client API, meaning that anyone can
+# query the room directory. Defaults to 'false'.
#
-#allow_public_rooms_without_auth: false
+#allow_public_rooms_without_auth: true
-# If set to 'false', forbids any other homeserver to fetch the server's public
-# rooms directory via federation. Defaults to 'true'.
+# If set to 'true', allows any other homeserver to fetch the server's public
+# rooms directory via federation. Defaults to 'false'.
#
-#allow_public_rooms_over_federation: false
+#allow_public_rooms_over_federation: true
# The default room version for newly created rooms.
#
@@ -328,6 +329,69 @@ listeners:
#
#user_ips_max_age: 14d
+# Message retention policy at the server level.
+#
+# Room admins and mods can define a retention period for their rooms using the
+# 'm.room.retention' state event, and server admins can cap this period by setting
+# the 'allowed_lifetime_min' and 'allowed_lifetime_max' config options.
+#
+# If this feature is enabled, Synapse will regularly look for and purge events
+# which are older than the room's maximum retention period. Synapse will also
+# filter events received over federation so that events that should have been
+# purged are ignored and not stored again.
+#
+retention:
+ # The message retention policies feature is disabled by default. Uncomment the
+ # following line to enable it.
+ #
+ #enabled: true
+
+ # Default retention policy. If set, Synapse will apply it to rooms that lack the
+ # 'm.room.retention' state event. Currently, the value of 'min_lifetime' doesn't
+ # matter much because Synapse doesn't take it into account yet.
+ #
+ #default_policy:
+ # min_lifetime: 1d
+ # max_lifetime: 1y
+
+ # Retention policy limits. If set, a user won't be able to send a
+ # 'm.room.retention' event which features a 'min_lifetime' or a 'max_lifetime'
+ # that's not within this range. This is especially useful in closed federations,
+ # in which server admins can make sure every federating server applies the same
+ # rules.
+ #
+ #allowed_lifetime_min: 1d
+ #allowed_lifetime_max: 1y
+
+ # Server admins can define the settings of the background jobs purging the
+ # events which lifetime has expired under the 'purge_jobs' section.
+ #
+ # If no configuration is provided, a single job will be set up to delete expired
+ # events in every room daily.
+ #
+ # Each job's configuration defines which range of message lifetimes the job
+ # takes care of. For example, if 'shortest_max_lifetime' is '2d' and
+ # 'longest_max_lifetime' is '3d', the job will handle purging expired events in
+ # rooms whose state defines a 'max_lifetime' that's both higher than 2 days, and
+ # lower than or equal to 3 days. Both the minimum and the maximum value of a
+ # range are optional, e.g. a job with no 'shortest_max_lifetime' and a
+ # 'longest_max_lifetime' of '3d' will handle every room with a retention policy
+ # which 'max_lifetime' is lower than or equal to three days.
+ #
+ # The rationale for this per-job configuration is that some rooms might have a
+ # retention policy with a low 'max_lifetime', where history needs to be purged
+ # of outdated messages on a very frequent basis (e.g. every 5min), but not want
+ # that purge to be performed by a job that's iterating over every room it knows,
+ # which would be quite heavy on the server.
+ #
+ #purge_jobs:
+ # - shortest_max_lifetime: 1d
+ # longest_max_lifetime: 3d
+ # interval: 5m:
+ # - shortest_max_lifetime: 3d
+ # longest_max_lifetime: 1y
+ # interval: 24h
+
## TLS ##
@@ -1270,8 +1334,23 @@ password_config:
# smtp_user: "exampleusername"
# smtp_pass: "examplepassword"
# require_transport_security: false
+#
+# # notif_from defines the "From" address to use when sending emails.
+# # It must be set if email sending is enabled.
+# #
+# # The placeholder '%(app)s' will be replaced by the application name,
+# # which is normally 'app_name' (below), but may be overridden by the
+# # Matrix client application.
+# #
+# # Note that the placeholder must be written '%(app)s', including the
+# # trailing 's'.
+# #
# notif_from: "Your Friendly %(app)s homeserver <noreply@example.com>"
-# app_name: Matrix
+#
+# # app_name defines the default value for '%(app)s' in notif_from. It
+# # defaults to 'Matrix'.
+# #
+# #app_name: my_branded_matrix_server
#
# # Enable email notifications by default
# #
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