Allow email subjects to be customised through Synapse's configuration (#7846)

4 files changed, 202 insertions, 39 deletions

diff --git a/changelog.d/7846.feature b/changelog.d/7846.feature
new file mode 100644
index 0000000000..997376fe42
--- /dev/null
+++ b/changelog.d/7846.feature
@@ -0,0 +1 @@
+Allow email subjects to be customised through Synapse's configuration.
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index 9d94495464..e059fd2c35 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -1949,8 +1949,8 @@ email:
   #
   #notif_from: "Your Friendly %(app)s homeserver <noreply@example.com>"
 
-  # app_name defines the default value for '%(app)s' in notif_from. It
-  # defaults to 'Matrix'.
+  # app_name defines the default value for '%(app)s' in notif_from and email
+  # subjects. It defaults to 'Matrix'.
   #
   #app_name: my_branded_matrix_server
 
@@ -2019,6 +2019,73 @@ email:
   #
   #template_dir: "res/templates"
 
+  # Subjects to use when sending emails from Synapse.
+  #
+  # The placeholder '%(app)s' will be replaced with the value of the 'app_name'
+  # setting above, or by a value dictated by the Matrix client application.
+  #
+  # If a subject isn't overridden in this configuration file, the value used as
+  # its example will be used.
+  #
+  #subjects:
+
+    # Subjects for notification emails.
+    #
+    # On top of the '%(app)s' placeholder, these can use the following
+    # placeholders:
+    #
+    #   * '%(person)s', which will be replaced by the display name of the user(s)
+    #      that sent the message(s), e.g. "Alice and Bob".
+    #   * '%(room)s', which will be replaced by the name of the room the
+    #      message(s) have been sent to, e.g. "My super room".
+    #
+    # See the example provided for each setting to see which placeholder can be
+    # used and how to use them.
+    #
+    # Subject to use to notify about one message from one or more user(s) in a
+    # room which has a name.
+    #message_from_person_in_room: "[%(app)s] You have a message on %(app)s from %(person)s in the %(room)s room..."
+    #
+    # Subject to use to notify about one message from one or more user(s) in a
+    # room which doesn't have a name.
+    #message_from_person: "[%(app)s] You have a message on %(app)s from %(person)s..."
+    #
+    # Subject to use to notify about multiple messages from one or more users in
+    # a room which doesn't have a name.
+    #messages_from_person: "[%(app)s] You have messages on %(app)s from %(person)s..."
+    #
+    # Subject to use to notify about multiple messages in a room which has a
+    # name.
+    #messages_in_room: "[%(app)s] You have messages on %(app)s in the %(room)s room..."
+    #
+    # Subject to use to notify about multiple messages in multiple rooms.
+    #messages_in_room_and_others: "[%(app)s] You have messages on %(app)s in the %(room)s room and others..."
+    #
+    # Subject to use to notify about multiple messages from multiple persons in
+    # multiple rooms. This is similar to the setting above except it's used when
+    # the room in which the notification was triggered has no name.
+    #messages_from_person_and_others: "[%(app)s] You have messages on %(app)s from %(person)s and others..."
+    #
+    # Subject to use to notify about an invite to a room which has a name.
+    #invite_from_person_to_room: "[%(app)s] %(person)s has invited you to join the %(room)s room on %(app)s..."
+    #
+    # Subject to use to notify about an invite to a room which doesn't have a
+    # name.
+    #invite_from_person: "[%(app)s] %(person)s has invited you to chat on %(app)s..."
+
+    # Subject for emails related to account administration.
+    #
+    # On top of the '%(app)s' placeholder, these one can use the
+    # '%(server_name)s' placeholder, which will be replaced by the value of the
+    # 'server_name' setting in your Synapse configuration.
+    #
+    # Subject to use when sending a password reset email.
+    #password_reset: "[%(server_name)s] Password reset"
+    #
+    # Subject to use when sending a verification email to assert an address's
+    # ownership.
+    #email_validation: "[%(server_name)s] Validate your email"
+
 
 # Password providers allow homeserver administrators to integrate
 # their Synapse installation with existing authentication methods
diff --git a/synapse/config/emailconfig.py b/synapse/config/emailconfig.py
index b1dc7ad502..a63acbdc63 100644
--- a/synapse/config/emailconfig.py
+++ b/synapse/config/emailconfig.py
@@ -22,6 +22,7 @@ import os
 from enum import Enum
 from typing import Optional
 
+import attr
 import pkg_resources
 
 from ._base import Config, ConfigError
@@ -32,6 +33,33 @@ Password reset emails are enabled on this homeserver due to a partial
     %s
 """
 
+DEFAULT_SUBJECTS = {
+    "message_from_person_in_room": "[%(app)s] You have a message on %(app)s from %(person)s in the %(room)s room...",
+    "message_from_person": "[%(app)s] You have a message on %(app)s from %(person)s...",
+    "messages_from_person": "[%(app)s] You have messages on %(app)s from %(person)s...",
+    "messages_in_room": "[%(app)s] You have messages on %(app)s in the %(room)s room...",
+    "messages_in_room_and_others": "[%(app)s] You have messages on %(app)s in the %(room)s room and others...",
+    "messages_from_person_and_others": "[%(app)s] You have messages on %(app)s from %(person)s and others...",
+    "invite_from_person": "[%(app)s] %(person)s has invited you to chat on %(app)s...",
+    "invite_from_person_to_room": "[%(app)s] %(person)s has invited you to join the %(room)s room on %(app)s...",
+    "password_reset": "[%(server_name)s] Password reset",
+    "email_validation": "[%(server_name)s] Validate your email",
+}
+
+
+@attr.s
+class EmailSubjectConfig:
+    message_from_person_in_room = attr.ib(type=str)
+    message_from_person = attr.ib(type=str)
+    messages_from_person = attr.ib(type=str)
+    messages_in_room = attr.ib(type=str)
+    messages_in_room_and_others = attr.ib(type=str)
+    messages_from_person_and_others = attr.ib(type=str)
+    invite_from_person = attr.ib(type=str)
+    invite_from_person_to_room = attr.ib(type=str)
+    password_reset = attr.ib(type=str)
+    email_validation = attr.ib(type=str)
+
 
 class EmailConfig(Config):
     section = "email"
@@ -294,8 +322,17 @@ class EmailConfig(Config):
                 if not os.path.isfile(p):
                     raise ConfigError("Unable to find email template file %s" % (p,))
 
+        subjects_config = email_config.get("subjects", {})
+        subjects = {}
+
+        for key, default in DEFAULT_SUBJECTS.items():
+            subjects[key] = subjects_config.get(key, default)
+
+        self.email_subjects = EmailSubjectConfig(**subjects)
+
     def generate_config_section(self, config_dir_path, server_name, **kwargs):
-        return """\
+        return (
+            """\
         # Configuration for sending emails from Synapse.
         #
         email:
@@ -323,17 +360,17 @@ class EmailConfig(Config):
           # 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,
+          # 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
+          # Note that the placeholder must be written '%%(app)s', including the
           # trailing 's'.
           #
-          #notif_from: "Your Friendly %(app)s homeserver <noreply@example.com>"
+          #notif_from: "Your Friendly %%(app)s homeserver <noreply@example.com>"
 
-          # app_name defines the default value for '%(app)s' in notif_from. It
-          # defaults to 'Matrix'.
+          # app_name defines the default value for '%%(app)s' in notif_from and email
+          # subjects. It defaults to 'Matrix'.
           #
           #app_name: my_branded_matrix_server
 
@@ -401,7 +438,76 @@ class EmailConfig(Config):
           # https://github.com/matrix-org/synapse/tree/master/synapse/res/templates
           #
           #template_dir: "res/templates"
+
+          # Subjects to use when sending emails from Synapse.
+          #
+          # The placeholder '%%(app)s' will be replaced with the value of the 'app_name'
+          # setting above, or by a value dictated by the Matrix client application.
+          #
+          # If a subject isn't overridden in this configuration file, the value used as
+          # its example will be used.
+          #
+          #subjects:
+
+            # Subjects for notification emails.
+            #
+            # On top of the '%%(app)s' placeholder, these can use the following
+            # placeholders:
+            #
+            #   * '%%(person)s', which will be replaced by the display name of the user(s)
+            #      that sent the message(s), e.g. "Alice and Bob".
+            #   * '%%(room)s', which will be replaced by the name of the room the
+            #      message(s) have been sent to, e.g. "My super room".
+            #
+            # See the example provided for each setting to see which placeholder can be
+            # used and how to use them.
+            #
+            # Subject to use to notify about one message from one or more user(s) in a
+            # room which has a name.
+            #message_from_person_in_room: "%(message_from_person_in_room)s"
+            #
+            # Subject to use to notify about one message from one or more user(s) in a
+            # room which doesn't have a name.
+            #message_from_person: "%(message_from_person)s"
+            #
+            # Subject to use to notify about multiple messages from one or more users in
+            # a room which doesn't have a name.
+            #messages_from_person: "%(messages_from_person)s"
+            #
+            # Subject to use to notify about multiple messages in a room which has a
+            # name.
+            #messages_in_room: "%(messages_in_room)s"
+            #
+            # Subject to use to notify about multiple messages in multiple rooms.
+            #messages_in_room_and_others: "%(messages_in_room_and_others)s"
+            #
+            # Subject to use to notify about multiple messages from multiple persons in
+            # multiple rooms. This is similar to the setting above except it's used when
+            # the room in which the notification was triggered has no name.
+            #messages_from_person_and_others: "%(messages_from_person_and_others)s"
+            #
+            # Subject to use to notify about an invite to a room which has a name.
+            #invite_from_person_to_room: "%(invite_from_person_to_room)s"
+            #
+            # Subject to use to notify about an invite to a room which doesn't have a
+            # name.
+            #invite_from_person: "%(invite_from_person)s"
+
+            # Subject for emails related to account administration.
+            #
+            # On top of the '%%(app)s' placeholder, these one can use the
+            # '%%(server_name)s' placeholder, which will be replaced by the value of the
+            # 'server_name' setting in your Synapse configuration.
+            #
+            # Subject to use when sending a password reset email.
+            #password_reset: "%(password_reset)s"
+            #
+            # Subject to use when sending a verification email to assert an address's
+            # ownership.
+            #email_validation: "%(email_validation)s"
         """
+            % DEFAULT_SUBJECTS
+        )
 
 
 class ThreepidBehaviour(Enum):
diff --git a/synapse/push/mailer.py b/synapse/push/mailer.py
index a10dba0af6..af117fddf9 100644
--- a/synapse/push/mailer.py
+++ b/synapse/push/mailer.py
@@ -27,6 +27,7 @@ import jinja2
 
 from synapse.api.constants import EventTypes
 from synapse.api.errors import StoreError
+from synapse.config.emailconfig import EmailSubjectConfig
 from synapse.logging.context import make_deferred_yieldable
 from synapse.push.presentable_names import (
     calculate_room_name,
@@ -42,23 +43,6 @@ logger = logging.getLogger(__name__)
 T = TypeVar("T")
 
 
-MESSAGE_FROM_PERSON_IN_ROOM = (
-    "You have a message on %(app)s from %(person)s in the %(room)s room..."
-)
-MESSAGE_FROM_PERSON = "You have a message on %(app)s from %(person)s..."
-MESSAGES_FROM_PERSON = "You have messages on %(app)s from %(person)s..."
-MESSAGES_IN_ROOM = "You have messages on %(app)s in the %(room)s room..."
-MESSAGES_IN_ROOM_AND_OTHERS = (
-    "You have messages on %(app)s in the %(room)s room and others..."
-)
-MESSAGES_FROM_PERSON_AND_OTHERS = (
-    "You have messages on %(app)s from %(person)s and others..."
-)
-INVITE_FROM_PERSON_TO_ROOM = (
-    "%(person)s has invited you to join the %(room)s room on %(app)s..."
-)
-INVITE_FROM_PERSON = "%(person)s has invited you to chat on %(app)s..."
-
 CONTEXT_BEFORE = 1
 CONTEXT_AFTER = 1
 
@@ -121,6 +105,7 @@ class Mailer(object):
         self.state_handler = self.hs.get_state_handler()
         self.storage = hs.get_storage()
         self.app_name = app_name
+        self.email_subjects = hs.config.email_subjects  # type: EmailSubjectConfig
 
         logger.info("Created Mailer for app_name %s" % app_name)
 
@@ -147,7 +132,8 @@ class Mailer(object):
 
         await self.send_email(
             email_address,
-            "[%s] Password Reset" % self.hs.config.server_name,
+            self.email_subjects.password_reset
+            % {"server_name": self.hs.config.server_name},
             template_vars,
         )
 
@@ -174,7 +160,8 @@ class Mailer(object):
 
         await self.send_email(
             email_address,
-            "[%s] Register your Email Address" % self.hs.config.server_name,
+            self.email_subjects.email_validation
+            % {"server_name": self.hs.config.server_name},
             template_vars,
         )
 
@@ -202,7 +189,8 @@ class Mailer(object):
 
         await self.send_email(
             email_address,
-            "[%s] Validate Your Email" % self.hs.config.server_name,
+            self.email_subjects.email_validation
+            % {"server_name": self.hs.config.server_name},
             template_vars,
         )
 
@@ -273,9 +261,7 @@ class Mailer(object):
             "reason": reason,
         }
 
-        await self.send_email(
-            email_address, "[%s] %s" % (self.app_name, summary_text), template_vars
-        )
+        await self.send_email(email_address, summary_text, template_vars)
 
     async def send_email(self, email_address, subject, extra_template_vars):
         """Send an email with the given information and template text"""
@@ -482,12 +468,12 @@ class Mailer(object):
                 inviter_name = name_from_member_event(inviter_member_event)
 
                 if room_name is None:
-                    return INVITE_FROM_PERSON % {
+                    return self.email_subjects.invite_from_person % {
                         "person": inviter_name,
                         "app": self.app_name,
                     }
                 else:
-                    return INVITE_FROM_PERSON_TO_ROOM % {
+                    return self.email_subjects.invite_from_person_to_room % {
                         "person": inviter_name,
                         "room": room_name,
                         "app": self.app_name,
@@ -505,13 +491,13 @@ class Mailer(object):
                     sender_name = name_from_member_event(state_event)
 
                 if sender_name is not None and room_name is not None:
-                    return MESSAGE_FROM_PERSON_IN_ROOM % {
+                    return self.email_subjects.message_from_person_in_room % {
                         "person": sender_name,
                         "room": room_name,
                         "app": self.app_name,
                     }
                 elif sender_name is not None:
-                    return MESSAGE_FROM_PERSON % {
+                    return self.email_subjects.message_from_person % {
                         "person": sender_name,
                         "app": self.app_name,
                     }
@@ -519,7 +505,10 @@ class Mailer(object):
                 # There's more than one notification for this room, so just
                 # say there are several
                 if room_name is not None:
-                    return MESSAGES_IN_ROOM % {"room": room_name, "app": self.app_name}
+                    return self.email_subjects.messages_in_room % {
+                        "room": room_name,
+                        "app": self.app_name,
+                    }
                 else:
                     # If the room doesn't have a name, say who the messages
                     # are from explicitly to avoid, "messages in the Bob room"
@@ -537,7 +526,7 @@ class Mailer(object):
                         ]
                     )
 
-                    return MESSAGES_FROM_PERSON % {
+                    return self.email_subjects.messages_from_person % {
                         "person": descriptor_from_member_events(member_events.values()),
                         "app": self.app_name,
                     }
@@ -546,7 +535,7 @@ class Mailer(object):
 
             # ...but we still refer to the 'reason' room which triggered the mail
             if reason["room_name"] is not None:
-                return MESSAGES_IN_ROOM_AND_OTHERS % {
+                return self.email_subjects.messages_in_room_and_others % {
                     "room": reason["room_name"],
                     "app": self.app_name,
                 }
@@ -566,7 +555,7 @@ class Mailer(object):
                     [room_state_ids[room_id][("m.room.member", s)] for s in sender_ids]
                 )
 
-                return MESSAGES_FROM_PERSON_AND_OTHERS % {
+                return self.email_subjects.messages_from_person_and_others % {
                     "person": descriptor_from_member_events(member_events.values()),
                     "app": self.app_name,
                 }