diff --git a/synapse/server_notices/consent_server_notices.py b/synapse/server_notices/consent_server_notices.py
new file mode 100644
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+++ b/synapse/server_notices/consent_server_notices.py
@@ -0,0 +1,137 @@
+# -*- coding: utf-8 -*-
+# Copyright 2018 New Vector Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import logging
+
+from six import (iteritems, string_types)
+from twisted.internet import defer
+
+from synapse.api.errors import SynapseError
+from synapse.api.urls import ConsentURIBuilder
+from synapse.config import ConfigError
+from synapse.types import get_localpart_from_id
+
+logger = logging.getLogger(__name__)
+
+
+class ConsentServerNotices(object):
+ """Keeps track of whether we need to send users server_notices about
+ privacy policy consent, and sends one if we do.
+ """
+ def __init__(self, hs):
+ """
+
+ Args:
+ hs (synapse.server.HomeServer):
+ """
+ self._server_notices_manager = hs.get_server_notices_manager()
+ self._store = hs.get_datastore()
+
+ self._users_in_progress = set()
+
+ self._current_consent_version = hs.config.user_consent_version
+ self._server_notice_content = hs.config.user_consent_server_notice_content
+ self._send_to_guests = hs.config.user_consent_server_notice_to_guests
+
+ if self._server_notice_content is not None:
+ if not self._server_notices_manager.is_enabled():
+ raise ConfigError(
+ "user_consent configuration requires server notices, but "
+ "server notices are not enabled.",
+ )
+ if 'body' not in self._server_notice_content:
+ raise ConfigError(
+ "user_consent server_notice_consent must contain a 'body' "
+ "key.",
+ )
+
+ self._consent_uri_builder = ConsentURIBuilder(hs.config)
+
+ @defer.inlineCallbacks
+ def maybe_send_server_notice_to_user(self, user_id):
+ """Check if we need to send a notice to this user, and does so if so
+
+ Args:
+ user_id (str): user to check
+
+ Returns:
+ Deferred
+ """
+ if self._server_notice_content is None:
+ # not enabled
+ return
+
+ # make sure we don't send two messages to the same user at once
+ if user_id in self._users_in_progress:
+ return
+ self._users_in_progress.add(user_id)
+ try:
+ u = yield self._store.get_user_by_id(user_id)
+
+ if u["is_guest"] and not self._send_to_guests:
+ # don't send to guests
+ return
+
+ if u["consent_version"] == self._current_consent_version:
+ # user has already consented
+ return
+
+ if u["consent_server_notice_sent"] == self._current_consent_version:
+ # we've already sent a notice to the user
+ return
+
+ # need to send a message.
+ try:
+ consent_uri = self._consent_uri_builder.build_user_consent_uri(
+ get_localpart_from_id(user_id),
+ )
+ content = copy_with_str_subst(
+ self._server_notice_content, {
+ 'consent_uri': consent_uri,
+ },
+ )
+ yield self._server_notices_manager.send_notice(
+ user_id, content,
+ )
+ yield self._store.user_set_consent_server_notice_sent(
+ user_id, self._current_consent_version,
+ )
+ except SynapseError as e:
+ logger.error("Error sending server notice about user consent: %s", e)
+ finally:
+ self._users_in_progress.remove(user_id)
+
+
+def copy_with_str_subst(x, substitutions):
+ """Deep-copy a structure, carrying out string substitions on any strings
+
+ Args:
+ x (object): structure to be copied
+ substitutions (object): substitutions to be made - passed into the
+ string '%' operator
+
+ Returns:
+ copy of x
+ """
+ if isinstance(x, string_types):
+ return x % substitutions
+ if isinstance(x, dict):
+ return {
+ k: copy_with_str_subst(v, substitutions) for (k, v) in iteritems(x)
+ }
+ if isinstance(x, (list, tuple)):
+ return [copy_with_str_subst(y) for y in x]
+
+ # assume it's uninterested and can be shallow-copied.
+ return x
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