diff --git a/mautrix/bridge/commands/__init__.py b/mautrix/bridge/commands/__init__.py
index 894a0e28..5b558f48 100644
--- a/mautrix/bridge/commands/__init__.py
+++ b/mautrix/bridge/commands/__init__.py
@@ -1,6 +1,7 @@
 from .handler import (
     SECTION_ADMIN,
     SECTION_AUTH,
+    SECTION_CONNECTION,
     SECTION_GENERAL,
     CommandEvent,
     CommandHandler,
@@ -12,7 +13,15 @@
 )
 from .meta import cancel, help_cmd, unknown_command
 
-from . import admin, clean_rooms, crypto, delete_portal, login_matrix, manhole  # isort: skip
+from . import (  # isort: skip
+    admin,
+    clean_rooms,
+    crypto,
+    delete_portal,
+    login_matrix,
+    manhole,
+    relay,
+)
 
 __all__ = [
     "HelpSection",
@@ -25,4 +34,5 @@
     "SECTION_GENERAL",
     "SECTION_ADMIN",
     "SECTION_AUTH",
+    "SECTION_CONNECTION",
 ]
diff --git a/mautrix/bridge/commands/handler.py b/mautrix/bridge/commands/handler.py
index 77f7a707..daf68768 100644
--- a/mautrix/bridge/commands/handler.py
+++ b/mautrix/bridge/commands/handler.py
@@ -29,6 +29,7 @@
 SECTION_GENERAL = HelpSection("General", 0, "")
 SECTION_AUTH = HelpSection("Authentication", 10, "")
 SECTION_ADMIN = HelpSection("Administration", 50, "")
+SECTION_CONNECTION = HelpSection("Connection management", 15, "")
 
 
 def ensure_trailing_newline(s: str) -> str:
diff --git a/mautrix/bridge/commands/relay.py b/mautrix/bridge/commands/relay.py
new file mode 100644
index 00000000..31aa8c3f
--- /dev/null
+++ b/mautrix/bridge/commands/relay.py
@@ -0,0 +1,45 @@
+# Copyright (c) 2021 Tulir Asokan
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+from mautrix.types import EventID
+
+from .handler import SECTION_CONNECTION, CommandEvent, command_handler
+
+
+@command_handler(
+    needs_auth=True,
+    management_only=False,
+    name="set-relay",
+    help_section=SECTION_CONNECTION,
+    help_text="Relay messages in this room through your account.",
+)
+async def set_relay(evt: CommandEvent) -> EventID:
+    if not evt.config["bridge.relay.enabled"]:
+        return await evt.reply("Relay mode is not enable in this instance of the bridge.")
+    elif not evt.is_portal:
+        return await evt.reply("This is not a portal room.")
+    await evt.portal.set_relay_user(evt.sender)
+    return await evt.reply(
+        "Messages from non-logged-in users in this room will now be bridged "
+        "through your account."
+    )
+
+
+@command_handler(
+    needs_auth=True,
+    management_only=False,
+    name="unset-relay",
+    help_section=SECTION_CONNECTION,
+    help_text="Stop relaying messages in this room.",
+)
+async def unset_relay(evt: CommandEvent) -> EventID:
+    if not evt.config["bridge.relay.enabled"]:
+        return await evt.reply("Relay mode is not enable in this instance of the bridge.")
+    elif not evt.is_portal:
+        return await evt.reply("This is not a portal room.")
+    elif not evt.portal.has_relay:
+        return await evt.reply("This room does not have a relay user set.")
+    await evt.portal.set_relay_user(None)
+    return await evt.reply("Messages from non-logged-in users will no longer be bridged.")
diff --git a/mautrix/bridge/config.py b/mautrix/bridge/config.py
index 88439e37..916886d4 100644
--- a/mautrix/bridge/config.py
+++ b/mautrix/bridge/config.py
@@ -64,7 +64,7 @@ def forbidden_defaults(self) -> list[ForbiddenDefault]:
         )
 
     def do_update(self, helper: ConfigUpdateHelper) -> None:
-        copy = helper.copy
+        copy, copy_dict = helper.copy, helper.copy_dict
 
         copy("homeserver.address")
         copy("homeserver.domain")
@@ -100,6 +100,8 @@ def do_update(self, helper: ConfigUpdateHelper) -> None:
         copy("bridge.management_room_text.welcome_unconnected")
         copy("bridge.management_room_text.additional_help")
         copy("bridge.management_room_multiple_messages")
+        copy("bridge.relay.enabled")
+        copy_dict("bridge.relay.message_formats")
 
         copy("manhole.enabled")
         copy("manhole.path")
diff --git a/mautrix/bridge/portal.py b/mautrix/bridge/portal.py
index 083d1311..f1384a87 100644
--- a/mautrix/bridge/portal.py
+++ b/mautrix/bridge/portal.py
@@ -5,7 +5,7 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 from __future__ import annotations
 
-from typing import Any
+from typing import Any, Optional, Tuple
 from abc import ABC, abstractmethod
 from collections import defaultdict
 import asyncio
@@ -35,6 +35,7 @@ class BasePortal(ABC):
     encrypted: bool
     is_direct: bool
     backfill_lock: SimpleLock
+    _relay_user: Optional["br.BaseUser"]
 
     @abstractmethod
     async def save(self) -> None:
@@ -46,6 +47,33 @@ async def handle_matrix_message(
     ) -> None:
         pass
 
+    @property
+    @abstractmethod
+    async def has_relay(self) -> bool:
+        pass
+
+    @property
+    @abstractmethod
+    async def get_relay_user(self) -> Optional["br.BaseUser"]:
+        pass
+
+    @abstractmethod
+    async def set_relay_user(self, user: Optional["br.BaseUser"]) -> None:
+        pass
+
+    @abstractmethod
+    async def get_relay_sender(
+        self, sender: br.BaseUser, evt_identifier: str
+    ) -> Tuple[Optional["br.BaseUser"], bool]:
+        pass
+
+    @abstractmethod
+    async def apply_msg_format(self, sender: br.BaseUser, content: MessageEventContent) -> None:
+        pass
+
+    async def get_displayname(self, user: br.BaseUser) -> str:
+        return await self.main_intent.get_room_displayname(self.mxid, user.mxid) or user.mxid
+
     async def check_dm_encryption(self) -> bool | None:
         try:
             evt = await self.main_intent.get_state_event(self.mxid, EventType.ROOM_ENCRYPTION)